diff --git a/news/urllib3.vendor.rst b/news/urllib3.vendor.rst
new file mode 100644
index 000000000..10e1e7b45
--- /dev/null
+++ b/news/urllib3.vendor.rst
@@ -0,0 +1 @@
+Upgrade urllib3 to 1.26.2
diff --git a/src/pip/_vendor/urllib3/__init__.py b/src/pip/_vendor/urllib3/__init__.py
index 667e9bce9..fe86b59d7 100644
--- a/src/pip/_vendor/urllib3/__init__.py
+++ b/src/pip/_vendor/urllib3/__init__.py
@@ -1,28 +1,27 @@
 """
-urllib3 - Thread-safe connection pooling and re-using.
+Python HTTP library with thread-safe connection pooling, file post support, user friendly, and more
 """
 from __future__ import absolute_import
-import warnings
 
-from .connectionpool import HTTPConnectionPool, HTTPSConnectionPool, connection_from_url
+# Set default logging handler to avoid "No handler found" warnings.
+import logging
+import warnings
+from logging import NullHandler
 
 from . import exceptions
+from ._version import __version__
+from .connectionpool import HTTPConnectionPool, HTTPSConnectionPool, connection_from_url
 from .filepost import encode_multipart_formdata
 from .poolmanager import PoolManager, ProxyManager, proxy_from_url
 from .response import HTTPResponse
 from .util.request import make_headers
-from .util.url import get_host
-from .util.timeout import Timeout
 from .util.retry import Retry
-
-
-# Set default logging handler to avoid "No handler found" warnings.
-import logging
-from logging import NullHandler
+from .util.timeout import Timeout
+from .util.url import get_host
 
 __author__ = "Andrey Petrov (andrey.petrov@shazow.net)"
 __license__ = "MIT"
-__version__ = "1.25.9"
+__version__ = __version__
 
 __all__ = (
     "HTTPConnectionPool",
diff --git a/src/pip/_vendor/urllib3/_collections.py b/src/pip/_vendor/urllib3/_collections.py
index 019d1511d..da9857e98 100644
--- a/src/pip/_vendor/urllib3/_collections.py
+++ b/src/pip/_vendor/urllib3/_collections.py
@@ -17,9 +17,10 @@ except ImportError:  # Platform-specific: No threads available
 
 
 from collections import OrderedDict
-from .exceptions import InvalidHeader
-from .packages.six import iterkeys, itervalues, PY3
 
+from .exceptions import InvalidHeader
+from .packages import six
+from .packages.six import iterkeys, itervalues
 
 __all__ = ["RecentlyUsedContainer", "HTTPHeaderDict"]
 
@@ -174,7 +175,7 @@ class HTTPHeaderDict(MutableMapping):
     def __ne__(self, other):
         return not self.__eq__(other)
 
-    if not PY3:  # Python 2
+    if six.PY2:  # Python 2
         iterkeys = MutableMapping.iterkeys
         itervalues = MutableMapping.itervalues
 
@@ -190,7 +191,7 @@ class HTTPHeaderDict(MutableMapping):
 
     def pop(self, key, default=__marker):
         """D.pop(k[,d]) -> v, remove specified key and return the corresponding value.
-          If key is not found, d is returned if given, otherwise KeyError is raised.
+        If key is not found, d is returned if given, otherwise KeyError is raised.
         """
         # Using the MutableMapping function directly fails due to the private marker.
         # Using ordinary dict.pop would expose the internal structures.
diff --git a/src/pip/_vendor/urllib3/_version.py b/src/pip/_vendor/urllib3/_version.py
new file mode 100644
index 000000000..2dba29e3f
--- /dev/null
+++ b/src/pip/_vendor/urllib3/_version.py
@@ -0,0 +1,2 @@
+# This file is protected via CODEOWNERS
+__version__ = "1.26.2"
diff --git a/src/pip/_vendor/urllib3/connection.py b/src/pip/_vendor/urllib3/connection.py
index 6da1cf4b6..660d679c3 100644
--- a/src/pip/_vendor/urllib3/connection.py
+++ b/src/pip/_vendor/urllib3/connection.py
@@ -1,14 +1,18 @@
 from __future__ import absolute_import
-import re
+
 import datetime
 import logging
 import os
+import re
 import socket
-from socket import error as SocketError, timeout as SocketTimeout
 import warnings
+from socket import error as SocketError
+from socket import timeout as SocketTimeout
+
 from .packages import six
 from .packages.six.moves.http_client import HTTPConnection as _HTTPConnection
 from .packages.six.moves.http_client import HTTPException  # noqa: F401
+from .util.proxy import create_proxy_ssl_context
 
 try:  # Compiled with SSL?
     import ssl
@@ -30,27 +34,33 @@ except NameError:
         pass
 
 
+try:  # Python 3:
+    # Not a no-op, we're adding this to the namespace so it can be imported.
+    BrokenPipeError = BrokenPipeError
+except NameError:  # Python 2:
+
+    class BrokenPipeError(Exception):
+        pass
+
+
+from ._collections import HTTPHeaderDict  # noqa (historical, removed in v2)
+from ._version import __version__
 from .exceptions import (
-    NewConnectionError,
     ConnectTimeoutError,
+    NewConnectionError,
     SubjectAltNameWarning,
     SystemTimeWarning,
 )
-from .packages.ssl_match_hostname import match_hostname, CertificateError
-
+from .packages.ssl_match_hostname import CertificateError, match_hostname
+from .util import SKIP_HEADER, SKIPPABLE_HEADERS, connection
 from .util.ssl_ import (
-    resolve_cert_reqs,
-    resolve_ssl_version,
     assert_fingerprint,
     create_urllib3_context,
+    resolve_cert_reqs,
+    resolve_ssl_version,
     ssl_wrap_socket,
 )
 
-
-from .util import connection
-
-from ._collections import HTTPHeaderDict
-
 log = logging.getLogger(__name__)
 
 port_by_scheme = {"http": 80, "https": 443}
@@ -62,34 +72,30 @@ RECENT_DATE = datetime.date(2019, 1, 1)
 _CONTAINS_CONTROL_CHAR_RE = re.compile(r"[^-!#$%&'*+.^_`|~0-9a-zA-Z]")
 
 
-class DummyConnection(object):
-    """Used to detect a failed ConnectionCls import."""
-
-    pass
-
-
 class HTTPConnection(_HTTPConnection, object):
     """
-    Based on httplib.HTTPConnection but provides an extra constructor
+    Based on :class:`http.client.HTTPConnection` but provides an extra constructor
     backwards-compatibility layer between older and newer Pythons.
 
     Additional keyword parameters are used to configure attributes of the connection.
     Accepted parameters include:
 
-      - ``strict``: See the documentation on :class:`urllib3.connectionpool.HTTPConnectionPool`
-      - ``source_address``: Set the source address for the current connection.
-      - ``socket_options``: Set specific options on the underlying socket. If not specified, then
-        defaults are loaded from ``HTTPConnection.default_socket_options`` which includes disabling
-        Nagle's algorithm (sets TCP_NODELAY to 1) unless the connection is behind a proxy.
+    - ``strict``: See the documentation on :class:`urllib3.connectionpool.HTTPConnectionPool`
+    - ``source_address``: Set the source address for the current connection.
+    - ``socket_options``: Set specific options on the underlying socket. If not specified, then
+      defaults are loaded from ``HTTPConnection.default_socket_options`` which includes disabling
+      Nagle's algorithm (sets TCP_NODELAY to 1) unless the connection is behind a proxy.
 
-        For example, if you wish to enable TCP Keep Alive in addition to the defaults,
-        you might pass::
+      For example, if you wish to enable TCP Keep Alive in addition to the defaults,
+      you might pass:
 
-            HTTPConnection.default_socket_options + [
-                (socket.SOL_SOCKET, socket.SO_KEEPALIVE, 1),
-            ]
+      .. code-block:: python
 
-        Or you may want to disable the defaults by passing an empty list (e.g., ``[]``).
+         HTTPConnection.default_socket_options + [
+             (socket.SOL_SOCKET, socket.SO_KEEPALIVE, 1),
+         ]
+
+      Or you may want to disable the defaults by passing an empty list (e.g., ``[]``).
     """
 
     default_port = port_by_scheme["http"]
@@ -112,6 +118,10 @@ class HTTPConnection(_HTTPConnection, object):
         #: provided, we use the default options.
         self.socket_options = kw.pop("socket_options", self.default_socket_options)
 
+        # Proxy options provided by the user.
+        self.proxy = kw.pop("proxy", None)
+        self.proxy_config = kw.pop("proxy_config", None)
+
         _HTTPConnection.__init__(self, *args, **kw)
 
     @property
@@ -144,7 +154,7 @@ class HTTPConnection(_HTTPConnection, object):
         self._dns_host = value
 
     def _new_conn(self):
-        """ Establish a socket connection and set nodelay settings on it.
+        """Establish a socket connection and set nodelay settings on it.
 
         :return: New socket connection.
         """
@@ -174,10 +184,13 @@ class HTTPConnection(_HTTPConnection, object):
 
         return conn
 
+    def _is_using_tunnel(self):
+        # Google App Engine's httplib does not define _tunnel_host
+        return getattr(self, "_tunnel_host", None)
+
     def _prepare_conn(self, conn):
         self.sock = conn
-        # Google App Engine's httplib does not define _tunnel_host
-        if getattr(self, "_tunnel_host", None):
+        if self._is_using_tunnel():
             # TODO: Fix tunnel so it doesn't depend on self.sock state.
             self._tunnel()
             # Mark this connection as not reusable
@@ -188,7 +201,9 @@ class HTTPConnection(_HTTPConnection, object):
         self._prepare_conn(conn)
 
     def putrequest(self, method, url, *args, **kwargs):
-        """Send a request to the server"""
+        """"""
+        # Empty docstring because the indentation of CPython's implementation
+        # is broken but we don't want this method in our documentation.
         match = _CONTAINS_CONTROL_CHAR_RE.search(method)
         if match:
             raise ValueError(
@@ -198,17 +213,40 @@ class HTTPConnection(_HTTPConnection, object):
 
         return _HTTPConnection.putrequest(self, method, url, *args, **kwargs)
 
+    def putheader(self, header, *values):
+        """"""
+        if SKIP_HEADER not in values:
+            _HTTPConnection.putheader(self, header, *values)
+        elif six.ensure_str(header.lower()) not in SKIPPABLE_HEADERS:
+            raise ValueError(
+                "urllib3.util.SKIP_HEADER only supports '%s'"
+                % ("', '".join(map(str.title, sorted(SKIPPABLE_HEADERS))),)
+            )
+
+    def request(self, method, url, body=None, headers=None):
+        if headers is None:
+            headers = {}
+        else:
+            # Avoid modifying the headers passed into .request()
+            headers = headers.copy()
+        if "user-agent" not in (six.ensure_str(k.lower()) for k in headers):
+            headers["User-Agent"] = _get_default_user_agent()
+        super(HTTPConnection, self).request(method, url, body=body, headers=headers)
+
     def request_chunked(self, method, url, body=None, headers=None):
         """
         Alternative to the common request method, which sends the
         body with chunked encoding and not as one block
         """
-        headers = HTTPHeaderDict(headers if headers is not None else {})
-        skip_accept_encoding = "accept-encoding" in headers
-        skip_host = "host" in headers
+        headers = headers or {}
+        header_keys = set([six.ensure_str(k.lower()) for k in headers])
+        skip_accept_encoding = "accept-encoding" in header_keys
+        skip_host = "host" in header_keys
         self.putrequest(
             method, url, skip_accept_encoding=skip_accept_encoding, skip_host=skip_host
         )
+        if "user-agent" not in header_keys:
+            self.putheader("User-Agent", _get_default_user_agent())
         for header, value in headers.items():
             self.putheader(header, value)
         if "transfer-encoding" not in headers:
@@ -225,16 +263,22 @@ class HTTPConnection(_HTTPConnection, object):
                 if not isinstance(chunk, bytes):
                     chunk = chunk.encode("utf8")
                 len_str = hex(len(chunk))[2:]
-                self.send(len_str.encode("utf-8"))
-                self.send(b"\r\n")
-                self.send(chunk)
-                self.send(b"\r\n")
+                to_send = bytearray(len_str.encode())
+                to_send += b"\r\n"
+                to_send += chunk
+                to_send += b"\r\n"
+                self.send(to_send)
 
         # After the if clause, to always have a closed body
         self.send(b"0\r\n\r\n")
 
 
 class HTTPSConnection(HTTPConnection):
+    """
+    Many of the parameters to this constructor are passed to the underlying SSL
+    socket by means of :py:func:`urllib3.util.ssl_wrap_socket`.
+    """
+
     default_port = port_by_scheme["https"]
 
     cert_reqs = None
@@ -243,6 +287,7 @@ class HTTPSConnection(HTTPConnection):
     ca_cert_data = None
     ssl_version = None
     assert_fingerprint = None
+    tls_in_tls_required = False
 
     def __init__(
         self,
@@ -307,10 +352,15 @@ class HTTPSConnection(HTTPConnection):
         # Add certificate verification
         conn = self._new_conn()
         hostname = self.host
+        tls_in_tls = False
+
+        if self._is_using_tunnel():
+            if self.tls_in_tls_required:
+                conn = self._connect_tls_proxy(hostname, conn)
+                tls_in_tls = True
 
-        # Google App Engine's httplib does not define _tunnel_host
-        if getattr(self, "_tunnel_host", None):
             self.sock = conn
+
             # Calls self._set_hostport(), so self.host is
             # self._tunnel_host below.
             self._tunnel()
@@ -368,8 +418,26 @@ class HTTPSConnection(HTTPConnection):
             ca_cert_data=self.ca_cert_data,
             server_hostname=server_hostname,
             ssl_context=context,
+            tls_in_tls=tls_in_tls,
         )
 
+        # If we're using all defaults and the connection
+        # is TLSv1 or TLSv1.1 we throw a DeprecationWarning
+        # for the host.
+        if (
+            default_ssl_context
+            and self.ssl_version is None
+            and hasattr(self.sock, "version")
+            and self.sock.version() in {"TLSv1", "TLSv1.1"}
+        ):
+            warnings.warn(
+                "Negotiating TLSv1/TLSv1.1 by default is deprecated "
+                "and will be disabled in urllib3 v2.0.0. Connecting to "
+                "'%s' with '%s' can be enabled by explicitly opting-in "
+                "with 'ssl_version'" % (self.host, self.sock.version()),
+                DeprecationWarning,
+            )
+
         if self.assert_fingerprint:
             assert_fingerprint(
                 self.sock.getpeercert(binary_form=True), self.assert_fingerprint
@@ -400,6 +468,40 @@ class HTTPSConnection(HTTPConnection):
             or self.assert_fingerprint is not None
         )
 
+    def _connect_tls_proxy(self, hostname, conn):
+        """
+        Establish a TLS connection to the proxy using the provided SSL context.
+        """
+        proxy_config = self.proxy_config
+        ssl_context = proxy_config.ssl_context
+        if ssl_context:
+            # If the user provided a proxy context, we assume CA and client
+            # certificates have already been set
+            return ssl_wrap_socket(
+                sock=conn,
+                server_hostname=hostname,
+                ssl_context=ssl_context,
+            )
+
+        ssl_context = create_proxy_ssl_context(
+            self.ssl_version,
+            self.cert_reqs,
+            self.ca_certs,
+            self.ca_cert_dir,
+            self.ca_cert_data,
+        )
+
+        # If no cert was provided, use only the default options for server
+        # certificate validation
+        return ssl_wrap_socket(
+            sock=conn,
+            ca_certs=self.ca_certs,
+            ca_cert_dir=self.ca_cert_dir,
+            ca_cert_data=self.ca_cert_data,
+            server_hostname=hostname,
+            ssl_context=ssl_context,
+        )
+
 
 def _match_hostname(cert, asserted_hostname):
     try:
@@ -416,6 +518,16 @@ def _match_hostname(cert, asserted_hostname):
         raise
 
 
+def _get_default_user_agent():
+    return "python-urllib3/%s" % __version__
+
+
+class DummyConnection(object):
+    """Used to detect a failed ConnectionCls import."""
+
+    pass
+
+
 if not ssl:
     HTTPSConnection = DummyConnection  # noqa: F811
 
diff --git a/src/pip/_vendor/urllib3/connectionpool.py b/src/pip/_vendor/urllib3/connectionpool.py
index 5f044dbd9..4708c5bfc 100644
--- a/src/pip/_vendor/urllib3/connectionpool.py
+++ b/src/pip/_vendor/urllib3/connectionpool.py
@@ -1,57 +1,53 @@
 from __future__ import absolute_import
+
 import errno
 import logging
+import socket
 import sys
 import warnings
+from socket import error as SocketError
+from socket import timeout as SocketTimeout
 
-from socket import error as SocketError, timeout as SocketTimeout
-import socket
-
-
+from .connection import (
+    BaseSSLError,
+    BrokenPipeError,
+    DummyConnection,
+    HTTPConnection,
+    HTTPException,
+    HTTPSConnection,
+    VerifiedHTTPSConnection,
+    port_by_scheme,
+)
 from .exceptions import (
     ClosedPoolError,
-    ProtocolError,
     EmptyPoolError,
     HeaderParsingError,
     HostChangedError,
+    InsecureRequestWarning,
     LocationValueError,
     MaxRetryError,
+    NewConnectionError,
+    ProtocolError,
     ProxyError,
     ReadTimeoutError,
     SSLError,
     TimeoutError,
-    InsecureRequestWarning,
-    NewConnectionError,
 )
-from .packages.ssl_match_hostname import CertificateError
 from .packages import six
 from .packages.six.moves import queue
-from .connection import (
-    port_by_scheme,
-    DummyConnection,
-    HTTPConnection,
-    HTTPSConnection,
-    VerifiedHTTPSConnection,
-    HTTPException,
-    BaseSSLError,
-)
+from .packages.ssl_match_hostname import CertificateError
 from .request import RequestMethods
 from .response import HTTPResponse
-
 from .util.connection import is_connection_dropped
+from .util.proxy import connection_requires_http_tunnel
+from .util.queue import LifoQueue
 from .util.request import set_file_position
 from .util.response import assert_header_parsing
 from .util.retry import Retry
 from .util.timeout import Timeout
-from .util.url import (
-    get_host,
-    parse_url,
-    Url,
-    _normalize_host as normalize_host,
-    _encode_target,
-)
-from .util.queue import LifoQueue
-
+from .util.url import Url, _encode_target
+from .util.url import _normalize_host as normalize_host
+from .util.url import get_host, parse_url
 
 xrange = six.moves.xrange
 
@@ -111,16 +107,16 @@ class HTTPConnectionPool(ConnectionPool, RequestMethods):
 
     :param host:
         Host used for this HTTP Connection (e.g. "localhost"), passed into
-        :class:`httplib.HTTPConnection`.
+        :class:`http.client.HTTPConnection`.
 
     :param port:
         Port used for this HTTP Connection (None is equivalent to 80), passed
-        into :class:`httplib.HTTPConnection`.
+        into :class:`http.client.HTTPConnection`.
 
     :param strict:
         Causes BadStatusLine to be raised if the status line can't be parsed
         as a valid HTTP/1.0 or 1.1 status line, passed into
-        :class:`httplib.HTTPConnection`.
+        :class:`http.client.HTTPConnection`.
 
         .. note::
            Only works in Python 2. This parameter is ignored in Python 3.
@@ -154,11 +150,11 @@ class HTTPConnectionPool(ConnectionPool, RequestMethods):
 
     :param _proxy:
         Parsed proxy URL, should not be used directly, instead, see
-        :class:`urllib3.connectionpool.ProxyManager`"
+        :class:`urllib3.ProxyManager`
 
     :param _proxy_headers:
         A dictionary with proxy headers, should not be used directly,
-        instead, see :class:`urllib3.connectionpool.ProxyManager`"
+        instead, see :class:`urllib3.ProxyManager`
 
     :param \\**conn_kw:
         Additional parameters are used to create fresh :class:`urllib3.connection.HTTPConnection`,
@@ -181,6 +177,7 @@ class HTTPConnectionPool(ConnectionPool, RequestMethods):
         retries=None,
         _proxy=None,
         _proxy_headers=None,
+        _proxy_config=None,
         **conn_kw
     ):
         ConnectionPool.__init__(self, host, port)
@@ -202,6 +199,7 @@ class HTTPConnectionPool(ConnectionPool, RequestMethods):
 
         self.proxy = _proxy
         self.proxy_headers = _proxy_headers or {}
+        self.proxy_config = _proxy_config
 
         # Fill the queue up so that doing get() on it will block properly
         for _ in xrange(maxsize):
@@ -218,6 +216,9 @@ class HTTPConnectionPool(ConnectionPool, RequestMethods):
             # list.
             self.conn_kw.setdefault("socket_options", [])
 
+            self.conn_kw["proxy"] = self.proxy
+            self.conn_kw["proxy_config"] = self.proxy_config
+
     def _new_conn(self):
         """
         Return a fresh :class:`HTTPConnection`.
@@ -272,7 +273,7 @@ class HTTPConnectionPool(ConnectionPool, RequestMethods):
             conn.close()
             if getattr(conn, "auto_open", 1) == 0:
                 # This is a proxied connection that has been mutated by
-                # httplib._tunnel() and cannot be reused (since it would
+                # http.client._tunnel() and cannot be reused (since it would
                 # attempt to bypass the proxy)
                 conn = None
 
@@ -384,12 +385,30 @@ class HTTPConnectionPool(ConnectionPool, RequestMethods):
             self._raise_timeout(err=e, url=url, timeout_value=conn.timeout)
             raise
 
-        # conn.request() calls httplib.*.request, not the method in
+        # conn.request() calls http.client.*.request, not the method in
         # urllib3.request. It also calls makefile (recv) on the socket.
-        if chunked:
-            conn.request_chunked(method, url, **httplib_request_kw)
-        else:
-            conn.request(method, url, **httplib_request_kw)
+        try:
+            if chunked:
+                conn.request_chunked(method, url, **httplib_request_kw)
+            else:
+                conn.request(method, url, **httplib_request_kw)
+
+        # We are swallowing BrokenPipeError (errno.EPIPE) since the server is
+        # legitimately able to close the connection after sending a valid response.
+        # With this behaviour, the received response is still readable.
+        except BrokenPipeError:
+            # Python 3
+            pass
+        except IOError as e:
+            # Python 2 and macOS/Linux
+            # EPIPE and ESHUTDOWN are BrokenPipeError on Python 2, and EPROTOTYPE is needed on macOS
+            # https://erickt.github.io/blog/2014/11/19/adventures-in-debugging-a-potential-osx-kernel-bug/
+            if e.errno not in {
+                errno.EPIPE,
+                errno.ESHUTDOWN,
+                errno.EPROTOTYPE,
+            }:
+                raise
 
         # Reset the timeout for the recv() on the socket
         read_timeout = timeout_obj.read_timeout
@@ -532,10 +551,12 @@ class HTTPConnectionPool(ConnectionPool, RequestMethods):
         :param method:
             HTTP request method (such as GET, POST, PUT, etc.)
 
+        :param url:
+            The URL to perform the request on.
+
         :param body:
-            Data to send in the request body (useful for creating
-            POST requests, see HTTPConnectionPool.post_url for
-            more convenience).
+            Data to send in the request body, either :class:`str`, :class:`bytes`,
+            an iterable of :class:`str`/:class:`bytes`, or a file-like object.
 
         :param headers:
             Dictionary of custom headers to send, such as User-Agent,
@@ -565,7 +586,7 @@ class HTTPConnectionPool(ConnectionPool, RequestMethods):
 
         :param assert_same_host:
             If ``True``, will make sure that the host of the pool requests is
-            consistent else will raise HostChangedError. When False, you can
+            consistent else will raise HostChangedError. When ``False``, you can
             use the pool on an HTTP proxy and request foreign hosts.
 
         :param timeout:
@@ -602,6 +623,10 @@ class HTTPConnectionPool(ConnectionPool, RequestMethods):
             Additional parameters are passed to
             :meth:`urllib3.response.HTTPResponse.from_httplib`
         """
+
+        parsed_url = parse_url(url)
+        destination_scheme = parsed_url.scheme
+
         if headers is None:
             headers = self.headers
 
@@ -619,7 +644,7 @@ class HTTPConnectionPool(ConnectionPool, RequestMethods):
         if url.startswith("/"):
             url = six.ensure_str(_encode_target(url))
         else:
-            url = six.ensure_str(parse_url(url).url)
+            url = six.ensure_str(parsed_url.url)
 
         conn = None
 
@@ -634,10 +659,14 @@ class HTTPConnectionPool(ConnectionPool, RequestMethods):
         # [1] <https://github.com/urllib3/urllib3/issues/651>
         release_this_conn = release_conn
 
-        # Merge the proxy headers. Only do this in HTTP. We have to copy the
-        # headers dict so we can safely change it without those changes being
-        # reflected in anyone else's copy.
-        if self.scheme == "http":
+        http_tunnel_required = connection_requires_http_tunnel(
+            self.proxy, self.proxy_config, destination_scheme
+        )
+
+        # Merge the proxy headers. Only done when not using HTTP CONNECT. We
+        # have to copy the headers dict so we can safely change it without those
+        # changes being reflected in anyone else's copy.
+        if not http_tunnel_required:
             headers = headers.copy()
             headers.update(self.proxy_headers)
 
@@ -663,7 +692,7 @@ class HTTPConnectionPool(ConnectionPool, RequestMethods):
             is_new_proxy_conn = self.proxy is not None and not getattr(
                 conn, "sock", None
             )
-            if is_new_proxy_conn:
+            if is_new_proxy_conn and http_tunnel_required:
                 self._prepare_proxy(conn)
 
             # Make the request on the httplib connection object.
@@ -698,9 +727,11 @@ class HTTPConnectionPool(ConnectionPool, RequestMethods):
             # Everything went great!
             clean_exit = True
 
-        except queue.Empty:
-            # Timed out by queue.
-            raise EmptyPoolError(self, "No pool connections are available.")
+        except EmptyPoolError:
+            # Didn't get a connection from the pool, no need to clean up
+            clean_exit = True
+            release_this_conn = False
+            raise
 
         except (
             TimeoutError,
@@ -835,11 +866,7 @@ class HTTPSConnectionPool(HTTPConnectionPool):
     """
     Same as :class:`.HTTPConnectionPool`, but HTTPS.
 
-    When Python is compiled with the :mod:`ssl` module, then
-    :class:`.VerifiedHTTPSConnection` is used, which *can* verify certificates,
-    instead of :class:`.HTTPSConnection`.
-
-    :class:`.VerifiedHTTPSConnection` uses one of ``assert_fingerprint``,
+    :class:`.HTTPSConnection` uses one of ``assert_fingerprint``,
     ``assert_hostname`` and ``host`` in this order to verify connections.
     If ``assert_hostname`` is False, no verification is done.
 
@@ -923,15 +950,22 @@ class HTTPSConnectionPool(HTTPConnectionPool):
 
     def _prepare_proxy(self, conn):
         """
-        Establish tunnel connection early, because otherwise httplib
-        would improperly set Host: header to proxy's IP:port.
+        Establishes a tunnel connection through HTTP CONNECT.
+
+        Tunnel connection is established early because otherwise httplib would
+        improperly set Host: header to proxy's IP:port.
         """
+
         conn.set_tunnel(self._proxy_host, self.port, self.proxy_headers)
+
+        if self.proxy.scheme == "https":
+            conn.tls_in_tls_required = True
+
         conn.connect()
 
     def _new_conn(self):
         """
-        Return a fresh :class:`httplib.HTTPSConnection`.
+        Return a fresh :class:`http.client.HTTPSConnection`.
         """
         self.num_connections += 1
         log.debug(
diff --git a/src/pip/_vendor/urllib3/contrib/_securetransport/bindings.py b/src/pip/_vendor/urllib3/contrib/_securetransport/bindings.py
index d9b673331..42526be7f 100644
--- a/src/pip/_vendor/urllib3/contrib/_securetransport/bindings.py
+++ b/src/pip/_vendor/urllib3/contrib/_securetransport/bindings.py
@@ -32,30 +32,26 @@ license and by oscrypto's:
 from __future__ import absolute_import
 
 import platform
-from ctypes.util import find_library
 from ctypes import (
-    c_void_p,
-    c_int32,
-    c_char_p,
-    c_size_t,
+    CDLL,
+    CFUNCTYPE,
+    POINTER,
+    c_bool,
     c_byte,
+    c_char_p,
+    c_int32,
+    c_long,
+    c_size_t,
     c_uint32,
     c_ulong,
-    c_long,
-    c_bool,
+    c_void_p,
 )
-from ctypes import CDLL, POINTER, CFUNCTYPE
+from ctypes.util import find_library
 
+from pip._vendor.urllib3.packages.six import raise_from
 
-security_path = find_library("Security")
-if not security_path:
-    raise ImportError("The library Security could not be found")
-
-
-core_foundation_path = find_library("CoreFoundation")
-if not core_foundation_path:
-    raise ImportError("The library CoreFoundation could not be found")
-
+if platform.system() != "Darwin":
+    raise ImportError("Only macOS is supported")
 
 version = platform.mac_ver()[0]
 version_info = tuple(map(int, version.split(".")))
@@ -65,8 +61,31 @@ if version_info < (10, 8):
         % (version_info[0], version_info[1])
     )
 
-Security = CDLL(security_path, use_errno=True)
-CoreFoundation = CDLL(core_foundation_path, use_errno=True)
+
+def load_cdll(name, macos10_16_path):
+    """Loads a CDLL by name, falling back to known path on 10.16+"""
+    try:
+        # Big Sur is technically 11 but we use 10.16 due to the Big Sur
+        # beta being labeled as 10.16.
+        if version_info >= (10, 16):
+            path = macos10_16_path
+        else:
+            path = find_library(name)
+        if not path:
+            raise OSError  # Caught and reraised as 'ImportError'
+        return CDLL(path, use_errno=True)
+    except OSError:
+        raise_from(ImportError("The library %s failed to load" % name), None)
+
+
+Security = load_cdll(
+    "Security", "/System/Library/Frameworks/Security.framework/Security"
+)
+CoreFoundation = load_cdll(
+    "CoreFoundation",
+    "/System/Library/Frameworks/CoreFoundation.framework/CoreFoundation",
+)
+
 
 Boolean = c_bool
 CFIndex = c_long
@@ -276,6 +295,13 @@ try:
     Security.SSLSetProtocolVersionMax.argtypes = [SSLContextRef, SSLProtocol]
     Security.SSLSetProtocolVersionMax.restype = OSStatus
 
+    try:
+        Security.SSLSetALPNProtocols.argtypes = [SSLContextRef, CFArrayRef]
+        Security.SSLSetALPNProtocols.restype = OSStatus
+    except AttributeError:
+        # Supported only in 10.12+
+        pass
+
     Security.SecCopyErrorMessageString.argtypes = [OSStatus, c_void_p]
     Security.SecCopyErrorMessageString.restype = CFStringRef
 
diff --git a/src/pip/_vendor/urllib3/contrib/_securetransport/low_level.py b/src/pip/_vendor/urllib3/contrib/_securetransport/low_level.py
index e60168cac..ed8120190 100644
--- a/src/pip/_vendor/urllib3/contrib/_securetransport/low_level.py
+++ b/src/pip/_vendor/urllib3/contrib/_securetransport/low_level.py
@@ -10,13 +10,13 @@ appropriate and useful assistance to the higher-level code.
 import base64
 import ctypes
 import itertools
-import re
 import os
+import re
 import ssl
+import struct
 import tempfile
 
-from .bindings import Security, CoreFoundation, CFConst
-
+from .bindings import CFConst, CoreFoundation, Security
 
 # This regular expression is used to grab PEM data out of a PEM bundle.
 _PEM_CERTS_RE = re.compile(
@@ -56,6 +56,51 @@ def _cf_dictionary_from_tuples(tuples):
     )
 
 
+def _cfstr(py_bstr):
+    """
+    Given a Python binary data, create a CFString.
+    The string must be CFReleased by the caller.
+    """
+    c_str = ctypes.c_char_p(py_bstr)
+    cf_str = CoreFoundation.CFStringCreateWithCString(
+        CoreFoundation.kCFAllocatorDefault,
+        c_str,
+        CFConst.kCFStringEncodingUTF8,
+    )
+    return cf_str
+
+
+def _create_cfstring_array(lst):
+    """
+    Given a list of Python binary data, create an associated CFMutableArray.
+    The array must be CFReleased by the caller.
+
+    Raises an ssl.SSLError on failure.
+    """
+    cf_arr = None
+    try:
+        cf_arr = CoreFoundation.CFArrayCreateMutable(
+            CoreFoundation.kCFAllocatorDefault,
+            0,
+            ctypes.byref(CoreFoundation.kCFTypeArrayCallBacks),
+        )
+        if not cf_arr:
+            raise MemoryError("Unable to allocate memory!")
+        for item in lst:
+            cf_str = _cfstr(item)
+            if not cf_str:
+                raise MemoryError("Unable to allocate memory!")
+            try:
+                CoreFoundation.CFArrayAppendValue(cf_arr, cf_str)
+            finally:
+                CoreFoundation.CFRelease(cf_str)
+    except BaseException as e:
+        if cf_arr:
+            CoreFoundation.CFRelease(cf_arr)
+        raise ssl.SSLError("Unable to allocate array: %s" % (e,))
+    return cf_arr
+
+
 def _cf_string_to_unicode(value):
     """
     Creates a Unicode string from a CFString object. Used entirely for error
@@ -326,3 +371,26 @@ def _load_client_cert_chain(keychain, *paths):
     finally:
         for obj in itertools.chain(identities, certificates):
             CoreFoundation.CFRelease(obj)
+
+
+TLS_PROTOCOL_VERSIONS = {
+    "SSLv2": (0, 2),
+    "SSLv3": (3, 0),
+    "TLSv1": (3, 1),
+    "TLSv1.1": (3, 2),
+    "TLSv1.2": (3, 3),
+}
+
+
+def _build_tls_unknown_ca_alert(version):
+    """
+    Builds a TLS alert record for an unknown CA.
+    """
+    ver_maj, ver_min = TLS_PROTOCOL_VERSIONS[version]
+    severity_fatal = 0x02
+    description_unknown_ca = 0x30
+    msg = struct.pack(">BB", severity_fatal, description_unknown_ca)
+    msg_len = len(msg)
+    record_type_alert = 0x15
+    record = struct.pack(">BBBH", record_type_alert, ver_maj, ver_min, msg_len) + msg
+    return record
diff --git a/src/pip/_vendor/urllib3/contrib/appengine.py b/src/pip/_vendor/urllib3/contrib/appengine.py
index d09d2be64..b9d2a6907 100644
--- a/src/pip/_vendor/urllib3/contrib/appengine.py
+++ b/src/pip/_vendor/urllib3/contrib/appengine.py
@@ -39,24 +39,24 @@ urllib3 on Google App Engine:
 """
 
 from __future__ import absolute_import
+
 import io
 import logging
 import warnings
-from ..packages.six.moves.urllib.parse import urljoin
 
 from ..exceptions import (
     HTTPError,
     HTTPWarning,
     MaxRetryError,
     ProtocolError,
-    TimeoutError,
     SSLError,
+    TimeoutError,
 )
-
+from ..packages.six.moves.urllib.parse import urljoin
 from ..request import RequestMethods
 from ..response import HTTPResponse
-from ..util.timeout import Timeout
 from ..util.retry import Retry
+from ..util.timeout import Timeout
 from . import _appengine_environ
 
 try:
@@ -90,7 +90,7 @@ class AppEngineManager(RequestMethods):
         * If you attempt to use this on App Engine Flexible, as full socket
           support is available.
         * If a request size is more than 10 megabytes.
-        * If a response size is more than 32 megabtyes.
+        * If a response size is more than 32 megabytes.
         * If you use an unsupported request method such as OPTIONS.
 
     Beyond those cases, it will raise normal urllib3 errors.
diff --git a/src/pip/_vendor/urllib3/contrib/ntlmpool.py b/src/pip/_vendor/urllib3/contrib/ntlmpool.py
index 1fd242a6e..b2df45dcf 100644
--- a/src/pip/_vendor/urllib3/contrib/ntlmpool.py
+++ b/src/pip/_vendor/urllib3/contrib/ntlmpool.py
@@ -6,12 +6,12 @@ Issue #10, see: http://code.google.com/p/urllib3/issues/detail?id=10
 from __future__ import absolute_import
 
 from logging import getLogger
+
 from ntlm import ntlm
 
 from .. import HTTPSConnectionPool
 from ..packages.six.moves.http_client import HTTPSConnection
 
-
 log = getLogger(__name__)
 
 
diff --git a/src/pip/_vendor/urllib3/contrib/pyopenssl.py b/src/pip/_vendor/urllib3/contrib/pyopenssl.py
index d8fe0629c..bc5c114fa 100644
--- a/src/pip/_vendor/urllib3/contrib/pyopenssl.py
+++ b/src/pip/_vendor/urllib3/contrib/pyopenssl.py
@@ -1,27 +1,31 @@
 """
-SSL with SNI_-support for Python 2. Follow these instructions if you would
-like to verify SSL certificates in Python 2. Note, the default libraries do
+TLS with SNI_-support for Python 2. Follow these instructions if you would
+like to verify TLS certificates in Python 2. Note, the default libraries do
 *not* do certificate checking; you need to do additional work to validate
 certificates yourself.
 
 This needs the following packages installed:
 
-* pyOpenSSL (tested with 16.0.0)
-* cryptography (minimum 1.3.4, from pyopenssl)
-* idna (minimum 2.0, from cryptography)
+* `pyOpenSSL`_ (tested with 16.0.0)
+* `cryptography`_ (minimum 1.3.4, from pyopenssl)
+* `idna`_ (minimum 2.0, from cryptography)
 
 However, pyopenssl depends on cryptography, which depends on idna, so while we
 use all three directly here we end up having relatively few packages required.
 
 You can install them with the following command:
 
-    pip install pyopenssl cryptography idna
+.. code-block:: bash
+
+    $ python -m pip install pyopenssl cryptography idna
 
 To activate certificate checking, call
 :func:`~urllib3.contrib.pyopenssl.inject_into_urllib3` from your Python code
 before you begin making HTTP requests. This can be done in a ``sitecustomize``
 module, or at any other time before your application begins using ``urllib3``,
-like this::
+like this:
+
+.. code-block:: python
 
     try:
         import urllib3.contrib.pyopenssl
@@ -35,11 +39,11 @@ when the required modules are installed.
 Activating this module also has the positive side effect of disabling SSL/TLS
 compression in Python 2 (see `CRIME attack`_).
 
-If you want to configure the default list of supported cipher suites, you can
-set the ``urllib3.contrib.pyopenssl.DEFAULT_SSL_CIPHER_LIST`` variable.
-
 .. _sni: https://en.wikipedia.org/wiki/Server_Name_Indication
 .. _crime attack: https://en.wikipedia.org/wiki/CRIME_(security_exploit)
+.. _pyopenssl: https://www.pyopenssl.org
+.. _cryptography: https://cryptography.io
+.. _idna: https://github.com/kjd/idna
 """
 from __future__ import absolute_import
 
@@ -56,8 +60,9 @@ except ImportError:
         pass
 
 
-from socket import timeout, error as SocketError
 from io import BytesIO
+from socket import error as SocketError
+from socket import timeout
 
 try:  # Platform-specific: Python 2
     from socket import _fileobject
@@ -67,11 +72,10 @@ except ImportError:  # Platform-specific: Python 3
 
 import logging
 import ssl
-from ..packages import six
 import sys
 
 from .. import util
-
+from ..packages import six
 
 __all__ = ["inject_into_urllib3", "extract_from_urllib3"]
 
@@ -465,6 +469,10 @@ class PyOpenSSLContext(object):
             self._ctx.set_passwd_cb(lambda *_: password)
         self._ctx.use_privatekey_file(keyfile or certfile)
 
+    def set_alpn_protocols(self, protocols):
+        protocols = [six.ensure_binary(p) for p in protocols]
+        return self._ctx.set_alpn_protos(protocols)
+
     def wrap_socket(
         self,
         sock,
diff --git a/src/pip/_vendor/urllib3/contrib/securetransport.py b/src/pip/_vendor/urllib3/contrib/securetransport.py
index a6b7e94ad..8f058f507 100644
--- a/src/pip/_vendor/urllib3/contrib/securetransport.py
+++ b/src/pip/_vendor/urllib3/contrib/securetransport.py
@@ -29,6 +29,8 @@ library. An enormous debt is owed to him for blazing this trail for us. For
 that reason, this code should be considered to be covered both by urllib3's
 license and by oscrypto's:
 
+.. code-block::
+
     Copyright (c) 2015-2016 Will Bond <will@wbond.net>
 
     Permission is hereby granted, free of charge, to any person obtaining a
@@ -58,16 +60,21 @@ import os.path
 import shutil
 import socket
 import ssl
+import struct
 import threading
 import weakref
 
+from pip._vendor import six
+
 from .. import util
-from ._securetransport.bindings import Security, SecurityConst, CoreFoundation
+from ._securetransport.bindings import CoreFoundation, Security, SecurityConst
 from ._securetransport.low_level import (
     _assert_no_error,
+    _build_tls_unknown_ca_alert,
     _cert_array_from_pem,
-    _temporary_keychain,
+    _create_cfstring_array,
     _load_client_cert_chain,
+    _temporary_keychain,
 )
 
 try:  # Platform-specific: Python 2
@@ -374,16 +381,55 @@ class WrappedSocket(object):
         )
         _assert_no_error(result)
 
+    def _set_alpn_protocols(self, protocols):
+        """
+        Sets up the ALPN protocols on the context.
+        """
+        if not protocols:
+            return
+        protocols_arr = _create_cfstring_array(protocols)
+        try:
+            result = Security.SSLSetALPNProtocols(self.context, protocols_arr)
+            _assert_no_error(result)
+        finally:
+            CoreFoundation.CFRelease(protocols_arr)
+
     def _custom_validate(self, verify, trust_bundle):
         """
         Called when we have set custom validation. We do this in two cases:
         first, when cert validation is entirely disabled; and second, when
         using a custom trust DB.
+        Raises an SSLError if the connection is not trusted.
         """
         # If we disabled cert validation, just say: cool.
         if not verify:
             return
 
+        successes = (
+            SecurityConst.kSecTrustResultUnspecified,
+            SecurityConst.kSecTrustResultProceed,
+        )
+        try:
+            trust_result = self._evaluate_trust(trust_bundle)
+            if trust_result in successes:
+                return
+            reason = "error code: %d" % (trust_result,)
+        except Exception as e:
+            # Do not trust on error
+            reason = "exception: %r" % (e,)
+
+        # SecureTransport does not send an alert nor shuts down the connection.
+        rec = _build_tls_unknown_ca_alert(self.version())
+        self.socket.sendall(rec)
+        # close the connection immediately
+        # l_onoff = 1, activate linger
+        # l_linger = 0, linger for 0 seoncds
+        opts = struct.pack("ii", 1, 0)
+        self.socket.setsockopt(socket.SOL_SOCKET, socket.SO_LINGER, opts)
+        self.close()
+        raise ssl.SSLError("certificate verify failed, %s" % reason)
+
+    def _evaluate_trust(self, trust_bundle):
         # We want data in memory, so load it up.
         if os.path.isfile(trust_bundle):
             with open(trust_bundle, "rb") as f:
@@ -421,15 +467,7 @@ class WrappedSocket(object):
             if cert_array is not None:
                 CoreFoundation.CFRelease(cert_array)
 
-        # Ok, now we can look at what the result was.
-        successes = (
-            SecurityConst.kSecTrustResultUnspecified,
-            SecurityConst.kSecTrustResultProceed,
-        )
-        if trust_result.value not in successes:
-            raise ssl.SSLError(
-                "certificate verify failed, error code: %d" % trust_result.value
-            )
+        return trust_result.value
 
     def handshake(
         self,
@@ -441,6 +479,7 @@ class WrappedSocket(object):
         client_cert,
         client_key,
         client_key_passphrase,
+        alpn_protocols,
     ):
         """
         Actually performs the TLS handshake. This is run automatically by
@@ -481,6 +520,9 @@ class WrappedSocket(object):
         # Setup the ciphers.
         self._set_ciphers()
 
+        # Setup the ALPN protocols.
+        self._set_alpn_protocols(alpn_protocols)
+
         # Set the minimum and maximum TLS versions.
         result = Security.SSLSetProtocolVersionMin(self.context, min_version)
         _assert_no_error(result)
@@ -754,6 +796,7 @@ class SecureTransportContext(object):
         self._client_cert = None
         self._client_key = None
         self._client_key_passphrase = None
+        self._alpn_protocols = None
 
     @property
     def check_hostname(self):
@@ -831,6 +874,18 @@ class SecureTransportContext(object):
         self._client_key = keyfile
         self._client_cert_passphrase = password
 
+    def set_alpn_protocols(self, protocols):
+        """
+        Sets the ALPN protocols that will later be set on the context.
+
+        Raises a NotImplementedError if ALPN is not supported.
+        """
+        if not hasattr(Security, "SSLSetALPNProtocols"):
+            raise NotImplementedError(
+                "SecureTransport supports ALPN only in macOS 10.12+"
+            )
+        self._alpn_protocols = [six.ensure_binary(p) for p in protocols]
+
     def wrap_socket(
         self,
         sock,
@@ -860,5 +915,6 @@ class SecureTransportContext(object):
             self._client_cert,
             self._client_key,
             self._client_key_passphrase,
+            self._alpn_protocols,
         )
         return wrapped_socket
diff --git a/src/pip/_vendor/urllib3/contrib/socks.py b/src/pip/_vendor/urllib3/contrib/socks.py
index 9e97f7aa9..93df8325d 100644
--- a/src/pip/_vendor/urllib3/contrib/socks.py
+++ b/src/pip/_vendor/urllib3/contrib/socks.py
@@ -14,22 +14,26 @@ supports the following SOCKS features:
 - SOCKS5 with local DNS (``proxy_url='socks5://...``)
 - Usernames and passwords for the SOCKS proxy
 
- .. note::
-    It is recommended to use ``socks5h://`` or ``socks4a://`` schemes in
-    your ``proxy_url`` to ensure that DNS resolution is done from the remote
-    server instead of client-side when connecting to a domain name.
+.. note::
+   It is recommended to use ``socks5h://`` or ``socks4a://`` schemes in
+   your ``proxy_url`` to ensure that DNS resolution is done from the remote
+   server instead of client-side when connecting to a domain name.
 
 SOCKS4 supports IPv4 and domain names with the SOCKS4A extension. SOCKS5
 supports IPv4, IPv6, and domain names.
 
 When connecting to a SOCKS4 proxy the ``username`` portion of the ``proxy_url``
-will be sent as the ``userid`` section of the SOCKS request::
+will be sent as the ``userid`` section of the SOCKS request:
+
+.. code-block:: python
 
     proxy_url="socks4a://<userid>@proxy-host"
 
 When connecting to a SOCKS5 proxy the ``username`` and ``password`` portion
 of the ``proxy_url`` will be sent as the username/password to authenticate
-with the proxy::
+with the proxy:
+
+.. code-block:: python
 
     proxy_url="socks5h://<username>:<password>@proxy-host"
 
@@ -40,6 +44,7 @@ try:
     import socks
 except ImportError:
     import warnings
+
     from ..exceptions import DependencyWarning
 
     warnings.warn(
@@ -52,7 +57,8 @@ except ImportError:
     )
     raise
 
-from socket import error as SocketError, timeout as SocketTimeout
+from socket import error as SocketError
+from socket import timeout as SocketTimeout
 
 from ..connection import HTTPConnection, HTTPSConnection
 from ..connectionpool import HTTPConnectionPool, HTTPSConnectionPool
diff --git a/src/pip/_vendor/urllib3/exceptions.py b/src/pip/_vendor/urllib3/exceptions.py
index 5cc4d8a4f..d69958d5d 100644
--- a/src/pip/_vendor/urllib3/exceptions.py
+++ b/src/pip/_vendor/urllib3/exceptions.py
@@ -1,21 +1,24 @@
 from __future__ import absolute_import
+
 from .packages.six.moves.http_client import IncompleteRead as httplib_IncompleteRead
 
 # Base Exceptions
 
 
 class HTTPError(Exception):
-    "Base exception used by this module."
+    """Base exception used by this module."""
+
     pass
 
 
 class HTTPWarning(Warning):
-    "Base warning used by this module."
+    """Base warning used by this module."""
+
     pass
 
 
 class PoolError(HTTPError):
-    "Base exception for errors caused within a pool."
+    """Base exception for errors caused within a pool."""
 
     def __init__(self, pool, message):
         self.pool = pool
@@ -27,7 +30,7 @@ class PoolError(HTTPError):
 
 
 class RequestError(PoolError):
-    "Base exception for PoolErrors that have associated URLs."
+    """Base exception for PoolErrors that have associated URLs."""
 
     def __init__(self, pool, url, message):
         self.url = url
@@ -39,12 +42,13 @@ class RequestError(PoolError):
 
 
 class SSLError(HTTPError):
-    "Raised when SSL certificate fails in an HTTPS connection."
+    """Raised when SSL certificate fails in an HTTPS connection."""
+
     pass
 
 
 class ProxyError(HTTPError):
-    "Raised when the connection to a proxy fails."
+    """Raised when the connection to a proxy fails."""
 
     def __init__(self, message, error, *args):
         super(ProxyError, self).__init__(message, error, *args)
@@ -52,12 +56,14 @@ class ProxyError(HTTPError):
 
 
 class DecodeError(HTTPError):
-    "Raised when automatic decoding based on Content-Type fails."
+    """Raised when automatic decoding based on Content-Type fails."""
+
     pass
 
 
 class ProtocolError(HTTPError):
-    "Raised when something unexpected happens mid-request/response."
+    """Raised when something unexpected happens mid-request/response."""
+
     pass
 
 
@@ -87,7 +93,7 @@ class MaxRetryError(RequestError):
 
 
 class HostChangedError(RequestError):
-    "Raised when an existing pool gets a request for a foreign host."
+    """Raised when an existing pool gets a request for a foreign host."""
 
     def __init__(self, pool, url, retries=3):
         message = "Tried to open a foreign host with url: %s" % url
@@ -96,13 +102,13 @@ class HostChangedError(RequestError):
 
 
 class TimeoutStateError(HTTPError):
-    """ Raised when passing an invalid state to a timeout """
+    """Raised when passing an invalid state to a timeout"""
 
     pass
 
 
 class TimeoutError(HTTPError):
-    """ Raised when a socket timeout error occurs.
+    """Raised when a socket timeout error occurs.
 
     Catching this error will catch both :exc:`ReadTimeoutErrors
     <ReadTimeoutError>` and :exc:`ConnectTimeoutErrors <ConnectTimeoutError>`.
@@ -112,39 +118,45 @@ class TimeoutError(HTTPError):
 
 
 class ReadTimeoutError(TimeoutError, RequestError):
-    "Raised when a socket timeout occurs while receiving data from a server"
+    """Raised when a socket timeout occurs while receiving data from a server"""
+
     pass
 
 
 # This timeout error does not have a URL attached and needs to inherit from the
 # base HTTPError
 class ConnectTimeoutError(TimeoutError):
-    "Raised when a socket timeout occurs while connecting to a server"
+    """Raised when a socket timeout occurs while connecting to a server"""
+
     pass
 
 
 class NewConnectionError(ConnectTimeoutError, PoolError):
-    "Raised when we fail to establish a new connection. Usually ECONNREFUSED."
+    """Raised when we fail to establish a new connection. Usually ECONNREFUSED."""
+
     pass
 
 
 class EmptyPoolError(PoolError):
-    "Raised when a pool runs out of connections and no more are allowed."
+    """Raised when a pool runs out of connections and no more are allowed."""
+
     pass
 
 
 class ClosedPoolError(PoolError):
-    "Raised when a request enters a pool after the pool has been closed."
+    """Raised when a request enters a pool after the pool has been closed."""
+
     pass
 
 
 class LocationValueError(ValueError, HTTPError):
-    "Raised when there is something wrong with a given URL input."
+    """Raised when there is something wrong with a given URL input."""
+
     pass
 
 
 class LocationParseError(LocationValueError):
-    "Raised when get_host or similar fails to parse the URL input."
+    """Raised when get_host or similar fails to parse the URL input."""
 
     def __init__(self, location):
         message = "Failed to parse: %s" % location
@@ -153,39 +165,56 @@ class LocationParseError(LocationValueError):
         self.location = location
 
 
+class URLSchemeUnknown(LocationValueError):
+    """Raised when a URL input has an unsupported scheme."""
+
+    def __init__(self, scheme):
+        message = "Not supported URL scheme %s" % scheme
+        super(URLSchemeUnknown, self).__init__(message)
+
+        self.scheme = scheme
+
+
 class ResponseError(HTTPError):
-    "Used as a container for an error reason supplied in a MaxRetryError."
+    """Used as a container for an error reason supplied in a MaxRetryError."""
+
     GENERIC_ERROR = "too many error responses"
     SPECIFIC_ERROR = "too many {status_code} error responses"
 
 
 class SecurityWarning(HTTPWarning):
-    "Warned when performing security reducing actions"
+    """Warned when performing security reducing actions"""
+
     pass
 
 
 class SubjectAltNameWarning(SecurityWarning):
-    "Warned when connecting to a host with a certificate missing a SAN."
+    """Warned when connecting to a host with a certificate missing a SAN."""
+
     pass
 
 
 class InsecureRequestWarning(SecurityWarning):
-    "Warned when making an unverified HTTPS request."
+    """Warned when making an unverified HTTPS request."""
+
     pass
 
 
 class SystemTimeWarning(SecurityWarning):
-    "Warned when system time is suspected to be wrong"
+    """Warned when system time is suspected to be wrong"""
+
     pass
 
 
 class InsecurePlatformWarning(SecurityWarning):
-    "Warned when certain SSL configuration is not available on a platform."
+    """Warned when certain TLS/SSL configuration is not available on a platform."""
+
     pass
 
 
 class SNIMissingWarning(HTTPWarning):
-    "Warned when making a HTTPS request without SNI available."
+    """Warned when making a HTTPS request without SNI available."""
+
     pass
 
 
@@ -198,29 +227,16 @@ class DependencyWarning(HTTPWarning):
     pass
 
 
-class InvalidProxyConfigurationWarning(HTTPWarning):
-    """
-    Warned when using an HTTPS proxy and an HTTPS URL. Currently
-    urllib3 doesn't support HTTPS proxies and the proxy will be
-    contacted via HTTP instead. This warning can be fixed by
-    changing your HTTPS proxy URL into an HTTP proxy URL.
-
-    If you encounter this warning read this:
-    https://github.com/urllib3/urllib3/issues/1850
-    """
-
-    pass
-
-
 class ResponseNotChunked(ProtocolError, ValueError):
-    "Response needs to be chunked in order to read it as chunks."
+    """Response needs to be chunked in order to read it as chunks."""
+
     pass
 
 
 class BodyNotHttplibCompatible(HTTPError):
     """
-    Body should be httplib.HTTPResponse like (have an fp attribute which
-    returns raw chunks) for read_chunked().
+    Body should be :class:`http.client.HTTPResponse` like
+    (have an fp attribute which returns raw chunks) for read_chunked().
     """
 
     pass
@@ -230,9 +246,8 @@ class IncompleteRead(HTTPError, httplib_IncompleteRead):
     """
     Response length doesn't match expected Content-Length
 
-    Subclass of http_client.IncompleteRead to allow int value
-    for `partial` to avoid creating large objects on streamed
-    reads.
+    Subclass of :class:`http.client.IncompleteRead` to allow int value
+    for ``partial`` to avoid creating large objects on streamed reads.
     """
 
     def __init__(self, partial, expected):
@@ -245,13 +260,32 @@ class IncompleteRead(HTTPError, httplib_IncompleteRead):
         )
 
 
+class InvalidChunkLength(HTTPError, httplib_IncompleteRead):
+    """Invalid chunk length in a chunked response."""
+
+    def __init__(self, response, length):
+        super(InvalidChunkLength, self).__init__(
+            response.tell(), response.length_remaining
+        )
+        self.response = response
+        self.length = length
+
+    def __repr__(self):
+        return "InvalidChunkLength(got length %r, %i bytes read)" % (
+            self.length,
+            self.partial,
+        )
+
+
 class InvalidHeader(HTTPError):
-    "The header provided was somehow invalid."
+    """The header provided was somehow invalid."""
+
     pass
 
 
-class ProxySchemeUnknown(AssertionError, ValueError):
-    "ProxyManager does not support the supplied scheme"
+class ProxySchemeUnknown(AssertionError, URLSchemeUnknown):
+    """ProxyManager does not support the supplied scheme"""
+
     # TODO(t-8ch): Stop inheriting from AssertionError in v2.0.
 
     def __init__(self, scheme):
@@ -259,8 +293,14 @@ class ProxySchemeUnknown(AssertionError, ValueError):
         super(ProxySchemeUnknown, self).__init__(message)
 
 
+class ProxySchemeUnsupported(ValueError):
+    """Fetching HTTPS resources through HTTPS proxies is unsupported"""
+
+    pass
+
+
 class HeaderParsingError(HTTPError):
-    "Raised by assert_header_parsing, but we convert it to a log.warning statement."
+    """Raised by assert_header_parsing, but we convert it to a log.warning statement."""
 
     def __init__(self, defects, unparsed_data):
         message = "%s, unparsed data: %r" % (defects or "Unknown", unparsed_data)
@@ -268,5 +308,6 @@ class HeaderParsingError(HTTPError):
 
 
 class UnrewindableBodyError(HTTPError):
-    "urllib3 encountered an error when trying to rewind a body"
+    """urllib3 encountered an error when trying to rewind a body"""
+
     pass
diff --git a/src/pip/_vendor/urllib3/fields.py b/src/pip/_vendor/urllib3/fields.py
index 8715b2202..9d630f491 100644
--- a/src/pip/_vendor/urllib3/fields.py
+++ b/src/pip/_vendor/urllib3/fields.py
@@ -1,4 +1,5 @@
 from __future__ import absolute_import
+
 import email.utils
 import mimetypes
 import re
@@ -26,7 +27,8 @@ def format_header_param_rfc2231(name, value):
     strategy defined in RFC 2231.
 
     Particularly useful for header parameters which might contain
-    non-ASCII values, like file names. This follows RFC 2388 Section 4.4.
+    non-ASCII values, like file names. This follows
+    `RFC 2388 Section 4.4 <https://tools.ietf.org/html/rfc2388#section-4.4>`_.
 
     :param name:
         The name of the parameter, a string expected to be ASCII only.
@@ -65,7 +67,6 @@ _HTML5_REPLACEMENTS = {
     u"\u0022": u"%22",
     # Replace "\" with "\\".
     u"\u005C": u"\u005C\u005C",
-    u"\u005C": u"\u005C\u005C",
 }
 
 # All control characters from 0x00 to 0x1F *except* 0x1B.
diff --git a/src/pip/_vendor/urllib3/filepost.py b/src/pip/_vendor/urllib3/filepost.py
index b7b00992c..36c9252c6 100644
--- a/src/pip/_vendor/urllib3/filepost.py
+++ b/src/pip/_vendor/urllib3/filepost.py
@@ -1,13 +1,13 @@
 from __future__ import absolute_import
+
 import binascii
 import codecs
 import os
-
 from io import BytesIO
 
+from .fields import RequestField
 from .packages import six
 from .packages.six import b
-from .fields import RequestField
 
 writer = codecs.lookup("utf-8")[3]
 
diff --git a/src/pip/_vendor/urllib3/packages/backports/makefile.py b/src/pip/_vendor/urllib3/packages/backports/makefile.py
index a3156a69c..b8fb2154b 100644
--- a/src/pip/_vendor/urllib3/packages/backports/makefile.py
+++ b/src/pip/_vendor/urllib3/packages/backports/makefile.py
@@ -7,7 +7,6 @@ Backports the Python 3 ``socket.makefile`` method for use with anything that
 wants to create a "fake" socket object.
 """
 import io
-
 from socket import SocketIO
 
 
diff --git a/src/pip/_vendor/urllib3/packages/ssl_match_hostname/__init__.py b/src/pip/_vendor/urllib3/packages/ssl_match_hostname/__init__.py
index 75b6bb1cf..6b12fd90a 100644
--- a/src/pip/_vendor/urllib3/packages/ssl_match_hostname/__init__.py
+++ b/src/pip/_vendor/urllib3/packages/ssl_match_hostname/__init__.py
@@ -10,10 +10,13 @@ try:
 except ImportError:
     try:
         # Backport of the function from a pypi module
-        from backports.ssl_match_hostname import CertificateError, match_hostname
+        from backports.ssl_match_hostname import (  # type: ignore
+            CertificateError,
+            match_hostname,
+        )
     except ImportError:
         # Our vendored copy
-        from ._implementation import CertificateError, match_hostname
+        from ._implementation import CertificateError, match_hostname  # type: ignore
 
 # Not needed, but documenting what we provide.
 __all__ = ("CertificateError", "match_hostname")
diff --git a/src/pip/_vendor/urllib3/poolmanager.py b/src/pip/_vendor/urllib3/poolmanager.py
index e2bd3bd8d..3a31a285b 100644
--- a/src/pip/_vendor/urllib3/poolmanager.py
+++ b/src/pip/_vendor/urllib3/poolmanager.py
@@ -1,24 +1,24 @@
 from __future__ import absolute_import
+
 import collections
 import functools
 import logging
-import warnings
 
 from ._collections import RecentlyUsedContainer
-from .connectionpool import HTTPConnectionPool, HTTPSConnectionPool
-from .connectionpool import port_by_scheme
+from .connectionpool import HTTPConnectionPool, HTTPSConnectionPool, port_by_scheme
 from .exceptions import (
     LocationValueError,
     MaxRetryError,
     ProxySchemeUnknown,
-    InvalidProxyConfigurationWarning,
+    ProxySchemeUnsupported,
+    URLSchemeUnknown,
 )
 from .packages import six
 from .packages.six.moves.urllib.parse import urljoin
 from .request import RequestMethods
-from .util.url import parse_url
+from .util.proxy import connection_requires_http_tunnel
 from .util.retry import Retry
-
+from .util.url import parse_url
 
 __all__ = ["PoolManager", "ProxyManager", "proxy_from_url"]
 
@@ -59,6 +59,7 @@ _key_fields = (
     "key_headers",  # dict
     "key__proxy",  # parsed proxy url
     "key__proxy_headers",  # dict
+    "key__proxy_config",  # class
     "key_socket_options",  # list of (level (int), optname (int), value (int or str)) tuples
     "key__socks_options",  # dict
     "key_assert_hostname",  # bool or string
@@ -70,6 +71,9 @@ _key_fields = (
 #: All custom key schemes should include the fields in this key at a minimum.
 PoolKey = collections.namedtuple("PoolKey", _key_fields)
 
+_proxy_config_fields = ("ssl_context", "use_forwarding_for_https")
+ProxyConfig = collections.namedtuple("ProxyConfig", _proxy_config_fields)
+
 
 def _default_key_normalizer(key_class, request_context):
     """
@@ -161,6 +165,7 @@ class PoolManager(RequestMethods):
     """
 
     proxy = None
+    proxy_config = None
 
     def __init__(self, num_pools=10, headers=None, **connection_pool_kw):
         RequestMethods.__init__(self, headers)
@@ -182,7 +187,7 @@ class PoolManager(RequestMethods):
 
     def _new_pool(self, scheme, host, port, request_context=None):
         """
-        Create a new :class:`ConnectionPool` based on host, port, scheme, and
+        Create a new :class:`urllib3.connectionpool.ConnectionPool` based on host, port, scheme, and
         any additional pool keyword arguments.
 
         If ``request_context`` is provided, it is provided as keyword arguments
@@ -218,7 +223,7 @@ class PoolManager(RequestMethods):
 
     def connection_from_host(self, host, port=None, scheme="http", pool_kwargs=None):
         """
-        Get a :class:`ConnectionPool` based on the host, port, and scheme.
+        Get a :class:`urllib3.connectionpool.ConnectionPool` based on the host, port, and scheme.
 
         If ``port`` isn't given, it will be derived from the ``scheme`` using
         ``urllib3.connectionpool.port_by_scheme``. If ``pool_kwargs`` is
@@ -241,20 +246,22 @@ class PoolManager(RequestMethods):
 
     def connection_from_context(self, request_context):
         """
-        Get a :class:`ConnectionPool` based on the request context.
+        Get a :class:`urllib3.connectionpool.ConnectionPool` based on the request context.
 
         ``request_context`` must at least contain the ``scheme`` key and its
         value must be a key in ``key_fn_by_scheme`` instance variable.
         """
         scheme = request_context["scheme"].lower()
-        pool_key_constructor = self.key_fn_by_scheme[scheme]
+        pool_key_constructor = self.key_fn_by_scheme.get(scheme)
+        if not pool_key_constructor:
+            raise URLSchemeUnknown(scheme)
         pool_key = pool_key_constructor(request_context)
 
         return self.connection_from_pool_key(pool_key, request_context=request_context)
 
     def connection_from_pool_key(self, pool_key, request_context=None):
         """
-        Get a :class:`ConnectionPool` based on the provided pool key.
+        Get a :class:`urllib3.connectionpool.ConnectionPool` based on the provided pool key.
 
         ``pool_key`` should be a namedtuple that only contains immutable
         objects. At a minimum it must have the ``scheme``, ``host``, and
@@ -312,9 +319,39 @@ class PoolManager(RequestMethods):
                     base_pool_kwargs[key] = value
         return base_pool_kwargs
 
+    def _proxy_requires_url_absolute_form(self, parsed_url):
+        """
+        Indicates if the proxy requires the complete destination URL in the
+        request.  Normally this is only needed when not using an HTTP CONNECT
+        tunnel.
+        """
+        if self.proxy is None:
+            return False
+
+        return not connection_requires_http_tunnel(
+            self.proxy, self.proxy_config, parsed_url.scheme
+        )
+
+    def _validate_proxy_scheme_url_selection(self, url_scheme):
+        """
+        Validates that were not attempting to do TLS in TLS connections on
+        Python2 or with unsupported SSL implementations.
+        """
+        if self.proxy is None or url_scheme != "https":
+            return
+
+        if self.proxy.scheme != "https":
+            return
+
+        if six.PY2 and not self.proxy_config.use_forwarding_for_https:
+            raise ProxySchemeUnsupported(
+                "Contacting HTTPS destinations through HTTPS proxies "
+                "'via CONNECT tunnels' is not supported in Python 2"
+            )
+
     def urlopen(self, method, url, redirect=True, **kw):
         """
-        Same as :meth:`urllib3.connectionpool.HTTPConnectionPool.urlopen`
+        Same as :meth:`urllib3.HTTPConnectionPool.urlopen`
         with custom cross-host redirect logic and only sends the request-uri
         portion of the ``url``.
 
@@ -322,6 +359,8 @@ class PoolManager(RequestMethods):
         :class:`urllib3.connectionpool.ConnectionPool` can be chosen for it.
         """
         u = parse_url(url)
+        self._validate_proxy_scheme_url_selection(u.scheme)
+
         conn = self.connection_from_host(u.host, port=u.port, scheme=u.scheme)
 
         kw["assert_same_host"] = False
@@ -330,7 +369,7 @@ class PoolManager(RequestMethods):
         if "headers" not in kw:
             kw["headers"] = self.headers.copy()
 
-        if self.proxy is not None and u.scheme == "http":
+        if self._proxy_requires_url_absolute_form(u):
             response = conn.urlopen(method, url, **kw)
         else:
             response = conn.urlopen(method, u.request_uri, **kw)
@@ -392,6 +431,19 @@ class ProxyManager(PoolManager):
         HTTPS/CONNECT case they are sent only once. Could be used for proxy
         authentication.
 
+    :param proxy_ssl_context:
+        The proxy SSL context is used to establish the TLS connection to the
+        proxy when using HTTPS proxies.
+
+    :param use_forwarding_for_https:
+        (Defaults to False) If set to True will forward requests to the HTTPS
+        proxy to be made on behalf of the client instead of creating a TLS
+        tunnel via the CONNECT method. **Enabling this flag means that request
+        and response headers and content will be visible from the HTTPS proxy**
+        whereas tunneling keeps request and response headers and content
+        private.  IP address, target hostname, SNI, and port are always visible
+        to an HTTPS proxy even when this flag is disabled.
+
     Example:
         >>> proxy = urllib3.ProxyManager('http://localhost:3128/')
         >>> r1 = proxy.request('GET', 'http://google.com/')
@@ -411,6 +463,8 @@ class ProxyManager(PoolManager):
         num_pools=10,
         headers=None,
         proxy_headers=None,
+        proxy_ssl_context=None,
+        use_forwarding_for_https=False,
         **connection_pool_kw
     ):
 
@@ -421,18 +475,22 @@ class ProxyManager(PoolManager):
                 proxy_url.port,
             )
         proxy = parse_url(proxy_url)
-        if not proxy.port:
-            port = port_by_scheme.get(proxy.scheme, 80)
-            proxy = proxy._replace(port=port)
 
         if proxy.scheme not in ("http", "https"):
             raise ProxySchemeUnknown(proxy.scheme)
 
+        if not proxy.port:
+            port = port_by_scheme.get(proxy.scheme, 80)
+            proxy = proxy._replace(port=port)
+
         self.proxy = proxy
         self.proxy_headers = proxy_headers or {}
+        self.proxy_ssl_context = proxy_ssl_context
+        self.proxy_config = ProxyConfig(proxy_ssl_context, use_forwarding_for_https)
 
         connection_pool_kw["_proxy"] = self.proxy
         connection_pool_kw["_proxy_headers"] = self.proxy_headers
+        connection_pool_kw["_proxy_config"] = self.proxy_config
 
         super(ProxyManager, self).__init__(num_pools, headers, **connection_pool_kw)
 
@@ -461,27 +519,13 @@ class ProxyManager(PoolManager):
             headers_.update(headers)
         return headers_
 
-    def _validate_proxy_scheme_url_selection(self, url_scheme):
-        if url_scheme == "https" and self.proxy.scheme == "https":
-            warnings.warn(
-                "Your proxy configuration specified an HTTPS scheme for the proxy. "
-                "Are you sure you want to use HTTPS to contact the proxy? "
-                "This most likely indicates an error in your configuration. "
-                "Read this issue for more info: "
-                "https://github.com/urllib3/urllib3/issues/1850",
-                InvalidProxyConfigurationWarning,
-                stacklevel=3,
-            )
-
     def urlopen(self, method, url, redirect=True, **kw):
         "Same as HTTP(S)ConnectionPool.urlopen, ``url`` must be absolute."
         u = parse_url(url)
-        self._validate_proxy_scheme_url_selection(u.scheme)
-
-        if u.scheme == "http":
-            # For proxied HTTPS requests, httplib sets the necessary headers
-            # on the CONNECT to the proxy. For HTTP, we'll definitely
-            # need to set 'Host' at the very least.
+        if not connection_requires_http_tunnel(self.proxy, self.proxy_config, u.scheme):
+            # For connections using HTTP CONNECT, httplib sets the necessary
+            # headers on the CONNECT to the proxy. If we're not using CONNECT,
+            # we'll definitely need to set 'Host' at the very least.
             headers = kw.get("headers", self.headers)
             kw["headers"] = self._set_proxy_headers(url, headers)
 
diff --git a/src/pip/_vendor/urllib3/request.py b/src/pip/_vendor/urllib3/request.py
index 55f160bbf..398386a5b 100644
--- a/src/pip/_vendor/urllib3/request.py
+++ b/src/pip/_vendor/urllib3/request.py
@@ -3,15 +3,14 @@ from __future__ import absolute_import
 from .filepost import encode_multipart_formdata
 from .packages.six.moves.urllib.parse import urlencode
 
-
 __all__ = ["RequestMethods"]
 
 
 class RequestMethods(object):
     """
     Convenience mixin for classes who implement a :meth:`urlopen` method, such
-    as :class:`~urllib3.connectionpool.HTTPConnectionPool` and
-    :class:`~urllib3.poolmanager.PoolManager`.
+    as :class:`urllib3.HTTPConnectionPool` and
+    :class:`urllib3.PoolManager`.
 
     Provides behavior for making common types of HTTP request methods and
     decides which type of request field encoding to use.
@@ -111,9 +110,9 @@ class RequestMethods(object):
         the body. This is useful for request methods like POST, PUT, PATCH, etc.
 
         When ``encode_multipart=True`` (default), then
-        :meth:`urllib3.filepost.encode_multipart_formdata` is used to encode
+        :func:`urllib3.encode_multipart_formdata` is used to encode
         the payload with the appropriate content type. Otherwise
-        :meth:`urllib.urlencode` is used with the
+        :func:`urllib.parse.urlencode` is used with the
         'application/x-www-form-urlencoded' content type.
 
         Multipart encoding must be used when posting files, and it's reasonably
diff --git a/src/pip/_vendor/urllib3/response.py b/src/pip/_vendor/urllib3/response.py
index 7dc9b93ca..38693f4fc 100644
--- a/src/pip/_vendor/urllib3/response.py
+++ b/src/pip/_vendor/urllib3/response.py
@@ -1,10 +1,11 @@
 from __future__ import absolute_import
-from contextlib import contextmanager
-import zlib
+
 import io
 import logging
-from socket import timeout as SocketTimeout
+import zlib
+from contextlib import contextmanager
 from socket import error as SocketError
+from socket import timeout as SocketTimeout
 
 try:
     import brotli
@@ -12,19 +13,20 @@ except ImportError:
     brotli = None
 
 from ._collections import HTTPHeaderDict
+from .connection import BaseSSLError, HTTPException
 from .exceptions import (
     BodyNotHttplibCompatible,
-    ProtocolError,
     DecodeError,
+    HTTPError,
+    IncompleteRead,
+    InvalidChunkLength,
+    InvalidHeader,
+    ProtocolError,
     ReadTimeoutError,
     ResponseNotChunked,
-    IncompleteRead,
-    InvalidHeader,
-    HTTPError,
+    SSLError,
 )
-from .packages.six import string_types as basestring, PY3
-from .packages.six.moves import http_client as httplib
-from .connection import HTTPException, BaseSSLError
+from .packages import six
 from .util.response import is_fp_closed, is_response_to_head
 
 log = logging.getLogger(__name__)
@@ -107,11 +109,10 @@ if brotli is not None:
         # are for 'brotlipy' and bottom branches for 'Brotli'
         def __init__(self):
             self._obj = brotli.Decompressor()
-
-        def decompress(self, data):
             if hasattr(self._obj, "decompress"):
-                return self._obj.decompress(data)
-            return self._obj.process(data)
+                self.decompress = self._obj.decompress
+            else:
+                self.decompress = self._obj.process
 
         def flush(self):
             if hasattr(self._obj, "flush"):
@@ -157,13 +158,13 @@ class HTTPResponse(io.IOBase):
     """
     HTTP Response container.
 
-    Backwards-compatible to httplib's HTTPResponse but the response ``body`` is
+    Backwards-compatible with :class:`http.client.HTTPResponse` but the response ``body`` is
     loaded and decoded on-demand when the ``data`` property is accessed.  This
     class is also compatible with the Python standard library's :mod:`io`
     module, and can hence be treated as a readable object in the context of that
     framework.
 
-    Extra parameters for behaviour not present in httplib.HTTPResponse:
+    Extra parameters for behaviour not present in :class:`http.client.HTTPResponse`:
 
     :param preload_content:
         If True, the response's body will be preloaded during construction.
@@ -173,7 +174,7 @@ class HTTPResponse(io.IOBase):
         'content-encoding' header.
 
     :param original_response:
-        When this HTTPResponse wrapper is generated from an httplib.HTTPResponse
+        When this HTTPResponse wrapper is generated from an :class:`http.client.HTTPResponse`
         object, it's convenient to include the original for debug purposes. It's
         otherwise unused.
 
@@ -233,7 +234,7 @@ class HTTPResponse(io.IOBase):
         self.msg = msg
         self._request_url = request_url
 
-        if body and isinstance(body, (basestring, bytes)):
+        if body and isinstance(body, (six.string_types, bytes)):
             self._body = body
 
         self._pool = pool
@@ -291,7 +292,7 @@ class HTTPResponse(io.IOBase):
 
     @property
     def data(self):
-        # For backwords-compat with earlier urllib3 0.4 and earlier.
+        # For backwards-compat with earlier urllib3 0.4 and earlier.
         if self._body:
             return self._body
 
@@ -308,8 +309,8 @@ class HTTPResponse(io.IOBase):
     def tell(self):
         """
         Obtain the number of bytes pulled over the wire so far. May differ from
-        the amount of content returned by :meth:``HTTPResponse.read`` if bytes
-        are encoded on the wire (e.g, compressed).
+        the amount of content returned by :meth:``urllib3.response.HTTPResponse.read``
+        if bytes are encoded on the wire (e.g, compressed).
         """
         return self._fp_bytes_read
 
@@ -443,10 +444,9 @@ class HTTPResponse(io.IOBase):
 
             except BaseSSLError as e:
                 # FIXME: Is there a better way to differentiate between SSLErrors?
-                if "read operation timed out" not in str(e):  # Defensive:
-                    # This shouldn't happen but just in case we're missing an edge
-                    # case, let's avoid swallowing SSL errors.
-                    raise
+                if "read operation timed out" not in str(e):
+                    # SSL errors related to framing/MAC get wrapped and reraised here
+                    raise SSLError(e)
 
                 raise ReadTimeoutError(self._pool, None, "Read timed out.")
 
@@ -480,7 +480,7 @@ class HTTPResponse(io.IOBase):
 
     def read(self, amt=None, decode_content=None, cache_content=False):
         """
-        Similar to :meth:`httplib.HTTPResponse.read`, but with two additional
+        Similar to :meth:`http.client.HTTPResponse.read`, but with two additional
         parameters: ``decode_content`` and ``cache_content``.
 
         :param amt:
@@ -581,7 +581,7 @@ class HTTPResponse(io.IOBase):
     @classmethod
     def from_httplib(ResponseCls, r, **response_kw):
         """
-        Given an :class:`httplib.HTTPResponse` instance ``r``, return a
+        Given an :class:`http.client.HTTPResponse` instance ``r``, return a
         corresponding :class:`urllib3.response.HTTPResponse` object.
 
         Remaining parameters are passed to the HTTPResponse constructor, along
@@ -590,11 +590,11 @@ class HTTPResponse(io.IOBase):
         headers = r.msg
 
         if not isinstance(headers, HTTPHeaderDict):
-            if PY3:
-                headers = HTTPHeaderDict(headers.items())
-            else:
+            if six.PY2:
                 # Python 2.7
                 headers = HTTPHeaderDict.from_httplib(headers)
+            else:
+                headers = HTTPHeaderDict(headers.items())
 
         # HTTPResponse objects in Python 3 don't have a .strict attribute
         strict = getattr(r, "strict", 0)
@@ -610,7 +610,7 @@ class HTTPResponse(io.IOBase):
         )
         return resp
 
-    # Backwards-compatibility methods for httplib.HTTPResponse
+    # Backwards-compatibility methods for http.client.HTTPResponse
     def getheaders(self):
         return self.headers
 
@@ -680,8 +680,8 @@ class HTTPResponse(io.IOBase):
     def supports_chunked_reads(self):
         """
         Checks if the underlying file-like object looks like a
-        httplib.HTTPResponse object. We do this by testing for the fp
-        attribute. If it is present we assume it returns raw chunks as
+        :class:`http.client.HTTPResponse` object. We do this by testing for
+        the fp attribute. If it is present we assume it returns raw chunks as
         processed by read_chunked().
         """
         return hasattr(self._fp, "fp")
@@ -698,7 +698,7 @@ class HTTPResponse(io.IOBase):
         except ValueError:
             # Invalid chunked protocol response, abort.
             self.close()
-            raise httplib.IncompleteRead(line)
+            raise InvalidChunkLength(self, line)
 
     def _handle_chunk(self, amt):
         returned_chunk = None
@@ -745,7 +745,7 @@ class HTTPResponse(io.IOBase):
             )
         if not self.supports_chunked_reads():
             raise BodyNotHttplibCompatible(
-                "Body should be httplib.HTTPResponse like. "
+                "Body should be http.client.HTTPResponse like. "
                 "It should have have an fp attribute which returns raw chunks."
             )
 
diff --git a/src/pip/_vendor/urllib3/util/__init__.py b/src/pip/_vendor/urllib3/util/__init__.py
index a96c73a9d..4547fc522 100644
--- a/src/pip/_vendor/urllib3/util/__init__.py
+++ b/src/pip/_vendor/urllib3/util/__init__.py
@@ -2,23 +2,23 @@ from __future__ import absolute_import
 
 # For backwards compatibility, provide imports that used to be here.
 from .connection import is_connection_dropped
-from .request import make_headers
+from .request import SKIP_HEADER, SKIPPABLE_HEADERS, make_headers
 from .response import is_fp_closed
+from .retry import Retry
 from .ssl_ import (
-    SSLContext,
+    ALPN_PROTOCOLS,
     HAS_SNI,
     IS_PYOPENSSL,
     IS_SECURETRANSPORT,
+    PROTOCOL_TLS,
+    SSLContext,
     assert_fingerprint,
     resolve_cert_reqs,
     resolve_ssl_version,
     ssl_wrap_socket,
-    PROTOCOL_TLS,
 )
-from .timeout import current_time, Timeout
-
-from .retry import Retry
-from .url import get_host, parse_url, split_first, Url
+from .timeout import Timeout, current_time
+from .url import Url, get_host, parse_url, split_first
 from .wait import wait_for_read, wait_for_write
 
 __all__ = (
@@ -27,6 +27,7 @@ __all__ = (
     "IS_SECURETRANSPORT",
     "SSLContext",
     "PROTOCOL_TLS",
+    "ALPN_PROTOCOLS",
     "Retry",
     "Timeout",
     "Url",
@@ -43,4 +44,6 @@ __all__ = (
     "ssl_wrap_socket",
     "wait_for_read",
     "wait_for_write",
+    "SKIP_HEADER",
+    "SKIPPABLE_HEADERS",
 )
diff --git a/src/pip/_vendor/urllib3/util/connection.py b/src/pip/_vendor/urllib3/util/connection.py
index 86f0a3b00..f1e5d37f8 100644
--- a/src/pip/_vendor/urllib3/util/connection.py
+++ b/src/pip/_vendor/urllib3/util/connection.py
@@ -1,7 +1,12 @@
 from __future__ import absolute_import
+
 import socket
-from .wait import NoWayToWaitForSocketError, wait_for_read
+
+from pip._vendor.urllib3.exceptions import LocationParseError
+
 from ..contrib import _appengine_environ
+from ..packages import six
+from .wait import NoWayToWaitForSocketError, wait_for_read
 
 
 def is_connection_dropped(conn):  # Platform-specific
@@ -9,7 +14,7 @@ def is_connection_dropped(conn):  # Platform-specific
     Returns True if the connection is dropped and should be closed.
 
     :param conn:
-        :class:`httplib.HTTPConnection` object.
+        :class:`http.client.HTTPConnection` object.
 
     Note: For platforms like AppEngine, this will always return ``False`` to
     let the platform handle connection recycling transparently for us.
@@ -42,7 +47,7 @@ def create_connection(
     port)``) and return the socket object.  Passing the optional
     *timeout* parameter will set the timeout on the socket instance
     before attempting to connect.  If no *timeout* is supplied, the
-    global default timeout setting returned by :func:`getdefaulttimeout`
+    global default timeout setting returned by :func:`socket.getdefaulttimeout`
     is used.  If *source_address* is set it must be a tuple of (host, port)
     for the socket to bind as a source address before making the connection.
     An host of '' or port 0 tells the OS to use the default.
@@ -58,6 +63,13 @@ def create_connection(
     # The original create_connection function always returns all records.
     family = allowed_gai_family()
 
+    try:
+        host.encode("idna")
+    except UnicodeError:
+        return six.raise_from(
+            LocationParseError(u"'%s', label empty or too long" % host), None
+        )
+
     for res in socket.getaddrinfo(host, port, family, socket.SOCK_STREAM):
         af, socktype, proto, canonname, sa = res
         sock = None
diff --git a/src/pip/_vendor/urllib3/util/proxy.py b/src/pip/_vendor/urllib3/util/proxy.py
new file mode 100644
index 000000000..34f884d5b
--- /dev/null
+++ b/src/pip/_vendor/urllib3/util/proxy.py
@@ -0,0 +1,56 @@
+from .ssl_ import create_urllib3_context, resolve_cert_reqs, resolve_ssl_version
+
+
+def connection_requires_http_tunnel(
+    proxy_url=None, proxy_config=None, destination_scheme=None
+):
+    """
+    Returns True if the connection requires an HTTP CONNECT through the proxy.
+
+    :param URL proxy_url:
+        URL of the proxy.
+    :param ProxyConfig proxy_config:
+        Proxy configuration from poolmanager.py
+    :param str destination_scheme:
+        The scheme of the destination. (i.e https, http, etc)
+    """
+    # If we're not using a proxy, no way to use a tunnel.
+    if proxy_url is None:
+        return False
+
+    # HTTP destinations never require tunneling, we always forward.
+    if destination_scheme == "http":
+        return False
+
+    # Support for forwarding with HTTPS proxies and HTTPS destinations.
+    if (
+        proxy_url.scheme == "https"
+        and proxy_config
+        and proxy_config.use_forwarding_for_https
+    ):
+        return False
+
+    # Otherwise always use a tunnel.
+    return True
+
+
+def create_proxy_ssl_context(
+    ssl_version, cert_reqs, ca_certs=None, ca_cert_dir=None, ca_cert_data=None
+):
+    """
+    Generates a default proxy ssl context if one hasn't been provided by the
+    user.
+    """
+    ssl_context = create_urllib3_context(
+        ssl_version=resolve_ssl_version(ssl_version),
+        cert_reqs=resolve_cert_reqs(cert_reqs),
+    )
+    if (
+        not ca_certs
+        and not ca_cert_dir
+        and not ca_cert_data
+        and hasattr(ssl_context, "load_default_certs")
+    ):
+        ssl_context.load_default_certs()
+
+    return ssl_context
diff --git a/src/pip/_vendor/urllib3/util/queue.py b/src/pip/_vendor/urllib3/util/queue.py
index d3d379a19..41784104e 100644
--- a/src/pip/_vendor/urllib3/util/queue.py
+++ b/src/pip/_vendor/urllib3/util/queue.py
@@ -1,4 +1,5 @@
 import collections
+
 from ..packages import six
 from ..packages.six.moves import queue
 
diff --git a/src/pip/_vendor/urllib3/util/request.py b/src/pip/_vendor/urllib3/util/request.py
index 3b7bb54da..25103383e 100644
--- a/src/pip/_vendor/urllib3/util/request.py
+++ b/src/pip/_vendor/urllib3/util/request.py
@@ -1,8 +1,16 @@
 from __future__ import absolute_import
+
 from base64 import b64encode
 
-from ..packages.six import b, integer_types
 from ..exceptions import UnrewindableBodyError
+from ..packages.six import b, integer_types
+
+# Pass as a value within ``headers`` to skip
+# emitting some HTTP headers that are added automatically.
+# The only headers that are supported are ``Accept-Encoding``,
+# ``Host``, and ``User-Agent``.
+SKIP_HEADER = "@@@SKIP_HEADER@@@"
+SKIPPABLE_HEADERS = frozenset(["accept-encoding", "host", "user-agent"])
 
 ACCEPT_ENCODING = "gzip,deflate"
 try:
diff --git a/src/pip/_vendor/urllib3/util/response.py b/src/pip/_vendor/urllib3/util/response.py
index 715868dd1..5ea609cce 100644
--- a/src/pip/_vendor/urllib3/util/response.py
+++ b/src/pip/_vendor/urllib3/util/response.py
@@ -1,7 +1,9 @@
 from __future__ import absolute_import
-from ..packages.six.moves import http_client as httplib
+
+from email.errors import MultipartInvariantViolationDefect, StartBoundaryNotFoundDefect
 
 from ..exceptions import HeaderParsingError
+from ..packages.six.moves import http_client as httplib
 
 
 def is_fp_closed(obj):
@@ -42,8 +44,7 @@ def assert_header_parsing(headers):
 
     Only works on Python 3.
 
-    :param headers: Headers to verify.
-    :type headers: `httplib.HTTPMessage`.
+    :param http.client.HTTPMessage headers: Headers to verify.
 
     :raises urllib3.exceptions.HeaderParsingError:
         If parsing errors are found.
@@ -66,6 +67,25 @@ def assert_header_parsing(headers):
 
             if isinstance(payload, (bytes, str)):
                 unparsed_data = payload
+    if defects:
+        # httplib is assuming a response body is available
+        # when parsing headers even when httplib only sends
+        # header data to parse_headers() This results in
+        # defects on multipart responses in particular.
+        # See: https://github.com/urllib3/urllib3/issues/800
+
+        # So we ignore the following defects:
+        # - StartBoundaryNotFoundDefect:
+        #     The claimed start boundary was never found.
+        # - MultipartInvariantViolationDefect:
+        #     A message claimed to be a multipart but no subparts were found.
+        defects = [
+            defect
+            for defect in defects
+            if not isinstance(
+                defect, (StartBoundaryNotFoundDefect, MultipartInvariantViolationDefect)
+            )
+        ]
 
     if defects or unparsed_data:
         raise HeaderParsingError(defects=defects, unparsed_data=unparsed_data)
@@ -76,8 +96,9 @@ def is_response_to_head(response):
     Checks whether the request of a response has been a HEAD-request.
     Handles the quirks of AppEngine.
 
-    :param conn:
-    :type conn: :class:`httplib.HTTPResponse`
+    :param http.client.HTTPResponse response:
+        Response to check if the originating request
+        used 'HEAD' as a method.
     """
     # FIXME: Can we do this somehow without accessing private httplib _method?
     method = response._method
diff --git a/src/pip/_vendor/urllib3/util/retry.py b/src/pip/_vendor/urllib3/util/retry.py
index ee30c91b1..ee51f922f 100644
--- a/src/pip/_vendor/urllib3/util/retry.py
+++ b/src/pip/_vendor/urllib3/util/retry.py
@@ -1,23 +1,24 @@
 from __future__ import absolute_import
-import time
+
+import email
 import logging
+import re
+import time
+import warnings
 from collections import namedtuple
 from itertools import takewhile
-import email
-import re
 
 from ..exceptions import (
     ConnectTimeoutError,
+    InvalidHeader,
     MaxRetryError,
     ProtocolError,
+    ProxyError,
     ReadTimeoutError,
     ResponseError,
-    InvalidHeader,
-    ProxyError,
 )
 from ..packages import six
 
-
 log = logging.getLogger(__name__)
 
 
@@ -27,8 +28,51 @@ RequestHistory = namedtuple(
 )
 
 
+# TODO: In v2 we can remove this sentinel and metaclass with deprecated options.
+_Default = object()
+
+
+class _RetryMeta(type):
+    @property
+    def DEFAULT_METHOD_WHITELIST(cls):
+        warnings.warn(
+            "Using 'Retry.DEFAULT_METHOD_WHITELIST' is deprecated and "
+            "will be removed in v2.0. Use 'Retry.DEFAULT_METHODS_ALLOWED' instead",
+            DeprecationWarning,
+        )
+        return cls.DEFAULT_ALLOWED_METHODS
+
+    @DEFAULT_METHOD_WHITELIST.setter
+    def DEFAULT_METHOD_WHITELIST(cls, value):
+        warnings.warn(
+            "Using 'Retry.DEFAULT_METHOD_WHITELIST' is deprecated and "
+            "will be removed in v2.0. Use 'Retry.DEFAULT_ALLOWED_METHODS' instead",
+            DeprecationWarning,
+        )
+        cls.DEFAULT_ALLOWED_METHODS = value
+
+    @property
+    def DEFAULT_REDIRECT_HEADERS_BLACKLIST(cls):
+        warnings.warn(
+            "Using 'Retry.DEFAULT_REDIRECT_HEADERS_BLACKLIST' is deprecated and "
+            "will be removed in v2.0. Use 'Retry.DEFAULT_REMOVE_HEADERS_ON_REDIRECT' instead",
+            DeprecationWarning,
+        )
+        return cls.DEFAULT_REMOVE_HEADERS_ON_REDIRECT
+
+    @DEFAULT_REDIRECT_HEADERS_BLACKLIST.setter
+    def DEFAULT_REDIRECT_HEADERS_BLACKLIST(cls, value):
+        warnings.warn(
+            "Using 'Retry.DEFAULT_REDIRECT_HEADERS_BLACKLIST' is deprecated and "
+            "will be removed in v2.0. Use 'Retry.DEFAULT_REMOVE_HEADERS_ON_REDIRECT' instead",
+            DeprecationWarning,
+        )
+        cls.DEFAULT_REMOVE_HEADERS_ON_REDIRECT = value
+
+
+@six.add_metaclass(_RetryMeta)
 class Retry(object):
-    """ Retry configuration.
+    """Retry configuration.
 
     Each retry attempt will create a new Retry object with updated values, so
     they can be safely reused.
@@ -54,8 +98,7 @@ class Retry(object):
         Total number of retries to allow. Takes precedence over other counts.
 
         Set to ``None`` to remove this constraint and fall back on other
-        counts. It's a good idea to set this to some sensibly-high value to
-        account for unexpected edge cases and avoid infinite retry loops.
+        counts.
 
         Set to ``0`` to fail on the first retry.
 
@@ -96,18 +139,35 @@ class Retry(object):
 
         Set to ``0`` to fail on the first retry of this type.
 
-    :param iterable method_whitelist:
+    :param int other:
+        How many times to retry on other errors.
+
+        Other errors are errors that are not connect, read, redirect or status errors.
+        These errors might be raised after the request was sent to the server, so the
+        request might have side-effects.
+
+        Set to ``0`` to fail on the first retry of this type.
+
+        If ``total`` is not set, it's a good idea to set this to 0 to account
+        for unexpected edge cases and avoid infinite retry loops.
+
+    :param iterable allowed_methods:
         Set of uppercased HTTP method verbs that we should retry on.
 
         By default, we only retry on methods which are considered to be
         idempotent (multiple requests with the same parameters end with the
-        same state). See :attr:`Retry.DEFAULT_METHOD_WHITELIST`.
+        same state). See :attr:`Retry.DEFAULT_ALLOWED_METHODS`.
 
         Set to a ``False`` value to retry on any verb.
 
+        .. warning::
+
+            Previously this parameter was named ``method_whitelist``, that
+            usage is deprecated in v1.26.0 and will be removed in v2.0.
+
     :param iterable status_forcelist:
         A set of integer HTTP status codes that we should force a retry on.
-        A retry is initiated if the request method is in ``method_whitelist``
+        A retry is initiated if the request method is in ``allowed_methods``
         and the response status code is in ``status_forcelist``.
 
         By default, this is disabled with ``None``.
@@ -148,13 +208,16 @@ class Retry(object):
         request.
     """
 
-    DEFAULT_METHOD_WHITELIST = frozenset(
+    #: Default methods to be used for ``allowed_methods``
+    DEFAULT_ALLOWED_METHODS = frozenset(
         ["HEAD", "GET", "PUT", "DELETE", "OPTIONS", "TRACE"]
     )
 
+    #: Default status codes to be used for ``status_forcelist``
     RETRY_AFTER_STATUS_CODES = frozenset([413, 429, 503])
 
-    DEFAULT_REDIRECT_HEADERS_BLACKLIST = frozenset(["Authorization"])
+    #: Default headers to be used for ``remove_headers_on_redirect``
+    DEFAULT_REMOVE_HEADERS_ON_REDIRECT = frozenset(["Authorization"])
 
     #: Maximum backoff time.
     BACKOFF_MAX = 120
@@ -166,20 +229,42 @@ class Retry(object):
         read=None,
         redirect=None,
         status=None,
-        method_whitelist=DEFAULT_METHOD_WHITELIST,
+        other=None,
+        allowed_methods=_Default,
         status_forcelist=None,
         backoff_factor=0,
         raise_on_redirect=True,
         raise_on_status=True,
         history=None,
         respect_retry_after_header=True,
-        remove_headers_on_redirect=DEFAULT_REDIRECT_HEADERS_BLACKLIST,
+        remove_headers_on_redirect=_Default,
+        # TODO: Deprecated, remove in v2.0
+        method_whitelist=_Default,
     ):
 
+        if method_whitelist is not _Default:
+            if allowed_methods is not _Default:
+                raise ValueError(
+                    "Using both 'allowed_methods' and "
+                    "'method_whitelist' together is not allowed. "
+                    "Instead only use 'allowed_methods'"
+                )
+            warnings.warn(
+                "Using 'method_whitelist' with Retry is deprecated and "
+                "will be removed in v2.0. Use 'allowed_methods' instead",
+                DeprecationWarning,
+            )
+            allowed_methods = method_whitelist
+        if allowed_methods is _Default:
+            allowed_methods = self.DEFAULT_ALLOWED_METHODS
+        if remove_headers_on_redirect is _Default:
+            remove_headers_on_redirect = self.DEFAULT_REMOVE_HEADERS_ON_REDIRECT
+
         self.total = total
         self.connect = connect
         self.read = read
         self.status = status
+        self.other = other
 
         if redirect is False or total is False:
             redirect = 0
@@ -187,7 +272,7 @@ class Retry(object):
 
         self.redirect = redirect
         self.status_forcelist = status_forcelist or set()
-        self.method_whitelist = method_whitelist
+        self.allowed_methods = allowed_methods
         self.backoff_factor = backoff_factor
         self.raise_on_redirect = raise_on_redirect
         self.raise_on_status = raise_on_status
@@ -204,7 +289,7 @@ class Retry(object):
             read=self.read,
             redirect=self.redirect,
             status=self.status,
-            method_whitelist=self.method_whitelist,
+            other=self.other,
             status_forcelist=self.status_forcelist,
             backoff_factor=self.backoff_factor,
             raise_on_redirect=self.raise_on_redirect,
@@ -213,6 +298,23 @@ class Retry(object):
             remove_headers_on_redirect=self.remove_headers_on_redirect,
             respect_retry_after_header=self.respect_retry_after_header,
         )
+
+        # TODO: If already given in **kw we use what's given to us
+        # If not given we need to figure out what to pass. We decide
+        # based on whether our class has the 'method_whitelist' property
+        # and if so we pass the deprecated 'method_whitelist' otherwise
+        # we use 'allowed_methods'. Remove in v2.0
+        if "method_whitelist" not in kw and "allowed_methods" not in kw:
+            if "method_whitelist" in self.__dict__:
+                warnings.warn(
+                    "Using 'method_whitelist' with Retry is deprecated and "
+                    "will be removed in v2.0. Use 'allowed_methods' instead",
+                    DeprecationWarning,
+                )
+                params["method_whitelist"] = self.allowed_methods
+            else:
+                params["allowed_methods"] = self.allowed_methods
+
         params.update(kw)
         return type(self)(**params)
 
@@ -231,7 +333,7 @@ class Retry(object):
         return new_retries
 
     def get_backoff_time(self):
-        """ Formula for computing the current backoff
+        """Formula for computing the current backoff
 
         :rtype: float
         """
@@ -252,10 +354,17 @@ class Retry(object):
         if re.match(r"^\s*[0-9]+\s*$", retry_after):
             seconds = int(retry_after)
         else:
-            retry_date_tuple = email.utils.parsedate(retry_after)
+            retry_date_tuple = email.utils.parsedate_tz(retry_after)
             if retry_date_tuple is None:
                 raise InvalidHeader("Invalid Retry-After header: %s" % retry_after)
-            retry_date = time.mktime(retry_date_tuple)
+            if retry_date_tuple[9] is None:  # Python 2
+                # Assume UTC if no timezone was specified
+                # On Python2.7, parsedate_tz returns None for a timezone offset
+                # instead of 0 if no timezone is given, where mktime_tz treats
+                # a None timezone offset as local time.
+                retry_date_tuple = retry_date_tuple[:9] + (0,) + retry_date_tuple[10:]
+
+            retry_date = email.utils.mktime_tz(retry_date_tuple)
             seconds = retry_date - time.time()
 
         if seconds < 0:
@@ -288,7 +397,7 @@ class Retry(object):
         time.sleep(backoff)
 
     def sleep(self, response=None):
-        """ Sleep between retry attempts.
+        """Sleep between retry attempts.
 
         This method will respect a server's ``Retry-After`` response header
         and sleep the duration of the time requested. If that is not present, it
@@ -304,7 +413,7 @@ class Retry(object):
         self._sleep_backoff()
 
     def _is_connection_error(self, err):
-        """ Errors when we're fairly sure that the server did not receive the
+        """Errors when we're fairly sure that the server did not receive the
         request, so it should be safe to retry.
         """
         if isinstance(err, ProxyError):
@@ -312,22 +421,33 @@ class Retry(object):
         return isinstance(err, ConnectTimeoutError)
 
     def _is_read_error(self, err):
-        """ Errors that occur after the request has been started, so we should
+        """Errors that occur after the request has been started, so we should
         assume that the server began processing it.
         """
         return isinstance(err, (ReadTimeoutError, ProtocolError))
 
     def _is_method_retryable(self, method):
-        """ Checks if a given HTTP method should be retried upon, depending if
-        it is included on the method whitelist.
+        """Checks if a given HTTP method should be retried upon, depending if
+        it is included in the allowed_methods
         """
-        if self.method_whitelist and method.upper() not in self.method_whitelist:
-            return False
+        # TODO: For now favor if the Retry implementation sets its own method_whitelist
+        # property outside of our constructor to avoid breaking custom implementations.
+        if "method_whitelist" in self.__dict__:
+            warnings.warn(
+                "Using 'method_whitelist' with Retry is deprecated and "
+                "will be removed in v2.0. Use 'allowed_methods' instead",
+                DeprecationWarning,
+            )
+            allowed_methods = self.method_whitelist
+        else:
+            allowed_methods = self.allowed_methods
 
+        if allowed_methods and method.upper() not in allowed_methods:
+            return False
         return True
 
     def is_retry(self, method, status_code, has_retry_after=False):
-        """ Is this method/status code retryable? (Based on whitelists and control
+        """Is this method/status code retryable? (Based on allowlists and control
         variables such as the number of total retries to allow, whether to
         respect the Retry-After header, whether this header is present, and
         whether the returned status code is on the list of status codes to
@@ -348,7 +468,14 @@ class Retry(object):
 
     def is_exhausted(self):
         """ Are we out of retries? """
-        retry_counts = (self.total, self.connect, self.read, self.redirect, self.status)
+        retry_counts = (
+            self.total,
+            self.connect,
+            self.read,
+            self.redirect,
+            self.status,
+            self.other,
+        )
         retry_counts = list(filter(None, retry_counts))
         if not retry_counts:
             return False
@@ -364,7 +491,7 @@ class Retry(object):
         _pool=None,
         _stacktrace=None,
     ):
-        """ Return a new Retry object with incremented retry counters.
+        """Return a new Retry object with incremented retry counters.
 
         :param response: A response object, or None, if the server did not
             return a response.
@@ -386,6 +513,7 @@ class Retry(object):
         read = self.read
         redirect = self.redirect
         status_count = self.status
+        other = self.other
         cause = "unknown"
         status = None
         redirect_location = None
@@ -404,6 +532,11 @@ class Retry(object):
             elif read is not None:
                 read -= 1
 
+        elif error:
+            # Other retry?
+            if other is not None:
+                other -= 1
+
         elif response and response.get_redirect_location():
             # Redirect retry?
             if redirect is not None:
@@ -414,7 +547,7 @@ class Retry(object):
 
         else:
             # Incrementing because of a server error like a 500 in
-            # status_forcelist and a the given method is in the whitelist
+            # status_forcelist and the given method is in the allowed_methods
             cause = ResponseError.GENERIC_ERROR
             if response and response.status:
                 if status_count is not None:
@@ -432,6 +565,7 @@ class Retry(object):
             read=read,
             redirect=redirect,
             status=status_count,
+            other=other,
             history=history,
         )
 
@@ -448,6 +582,20 @@ class Retry(object):
             "read={self.read}, redirect={self.redirect}, status={self.status})"
         ).format(cls=type(self), self=self)
 
+    def __getattr__(self, item):
+        if item == "method_whitelist":
+            # TODO: Remove this deprecated alias in v2.0
+            warnings.warn(
+                "Using 'method_whitelist' with Retry is deprecated and "
+                "will be removed in v2.0. Use 'allowed_methods' instead",
+                DeprecationWarning,
+            )
+            return self.allowed_methods
+        try:
+            return getattr(super(Retry, self), item)
+        except AttributeError:
+            return getattr(Retry, item)
+
 
 # For backwards compatibility (equivalent to pre-v1.9):
 Retry.DEFAULT = Retry(3)
diff --git a/src/pip/_vendor/urllib3/util/ssl_.py b/src/pip/_vendor/urllib3/util/ssl_.py
index d3b463d49..763da82bb 100644
--- a/src/pip/_vendor/urllib3/util/ssl_.py
+++ b/src/pip/_vendor/urllib3/util/ssl_.py
@@ -1,21 +1,27 @@
 from __future__ import absolute_import
-import errno
-import warnings
-import hmac
-import sys
 
+import hmac
+import os
+import sys
+import warnings
 from binascii import hexlify, unhexlify
 from hashlib import md5, sha1, sha256
 
-from .url import IPV4_RE, BRACELESS_IPV6_ADDRZ_RE
-from ..exceptions import SSLError, InsecurePlatformWarning, SNIMissingWarning
+from ..exceptions import (
+    InsecurePlatformWarning,
+    ProxySchemeUnsupported,
+    SNIMissingWarning,
+    SSLError,
+)
 from ..packages import six
-
+from .url import BRACELESS_IPV6_ADDRZ_RE, IPV4_RE
 
 SSLContext = None
+SSLTransport = None
 HAS_SNI = False
 IS_PYOPENSSL = False
 IS_SECURETRANSPORT = False
+ALPN_PROTOCOLS = ["http/1.1"]
 
 # Maps the length of a digest to a possible hash function producing this digest
 HASHFUNC_MAP = {32: md5, 40: sha1, 64: sha256}
@@ -29,8 +35,8 @@ def _const_compare_digest_backport(a, b):
     Returns True if the digests match, and False otherwise.
     """
     result = abs(len(a) - len(b))
-    for l, r in zip(bytearray(a), bytearray(b)):
-        result |= l ^ r
+    for left, right in zip(bytearray(a), bytearray(b)):
+        result |= left ^ right
     return result == 0
 
 
@@ -38,11 +44,21 @@ _const_compare_digest = getattr(hmac, "compare_digest", _const_compare_digest_ba
 
 try:  # Test for SSL features
     import ssl
-    from ssl import wrap_socket, CERT_REQUIRED
+    from ssl import CERT_REQUIRED, wrap_socket
+except ImportError:
+    pass
+
+try:
     from ssl import HAS_SNI  # Has SNI?
 except ImportError:
     pass
 
+try:
+    from .ssltransport import SSLTransport
+except ImportError:
+    pass
+
+
 try:  # Platform-specific: Python 3.6
     from ssl import PROTOCOL_TLS
 
@@ -57,12 +73,18 @@ except ImportError:
 
 
 try:
-    from ssl import OP_NO_SSLv2, OP_NO_SSLv3, OP_NO_COMPRESSION
+    from ssl import OP_NO_COMPRESSION, OP_NO_SSLv2, OP_NO_SSLv3
 except ImportError:
     OP_NO_SSLv2, OP_NO_SSLv3 = 0x1000000, 0x2000000
     OP_NO_COMPRESSION = 0x20000
 
 
+try:  # OP_NO_TICKET was added in Python 3.6
+    from ssl import OP_NO_TICKET
+except ImportError:
+    OP_NO_TICKET = 0x4000
+
+
 # A secure default.
 # Sources for more information on TLS ciphers:
 #
@@ -249,7 +271,7 @@ def create_urllib3_context(
         ``ssl.CERT_REQUIRED``.
     :param options:
         Specific OpenSSL options. These default to ``ssl.OP_NO_SSLv2``,
-        ``ssl.OP_NO_SSLv3``, ``ssl.OP_NO_COMPRESSION``.
+        ``ssl.OP_NO_SSLv3``, ``ssl.OP_NO_COMPRESSION``, and ``ssl.OP_NO_TICKET``.
     :param ciphers:
         Which cipher suites to allow the server to select.
     :returns:
@@ -272,6 +294,11 @@ def create_urllib3_context(
         # Disable compression to prevent CRIME attacks for OpenSSL 1.0+
         # (issue #309)
         options |= OP_NO_COMPRESSION
+        # TLSv1.2 only. Unless set explicitly, do not request tickets.
+        # This may save some bandwidth on wire, and although the ticket is encrypted,
+        # there is a risk associated with it being on wire,
+        # if the server is not rotating its ticketing keys properly.
+        options |= OP_NO_TICKET
 
     context.options |= options
 
@@ -293,6 +320,14 @@ def create_urllib3_context(
         # We do our own verification, including fingerprints and alternative
         # hostnames. So disable it here
         context.check_hostname = False
+
+    # Enable logging of TLS session keys via defacto standard environment variable
+    # 'SSLKEYLOGFILE', if the feature is available (Python 3.8+). Skip empty values.
+    if hasattr(context, "keylog_filename"):
+        sslkeylogfile = os.environ.get("SSLKEYLOGFILE")
+        if sslkeylogfile:
+            context.keylog_filename = sslkeylogfile
+
     return context
 
 
@@ -309,6 +344,7 @@ def ssl_wrap_socket(
     ca_cert_dir=None,
     key_password=None,
     ca_cert_data=None,
+    tls_in_tls=False,
 ):
     """
     All arguments except for server_hostname, ssl_context, and ca_cert_dir have
@@ -330,6 +366,8 @@ def ssl_wrap_socket(
     :param ca_cert_data:
         Optional string containing CA certificates in PEM format suitable for
         passing as the cadata parameter to SSLContext.load_verify_locations()
+    :param tls_in_tls:
+        Use SSLTransport to wrap the existing socket.
     """
     context = ssl_context
     if context is None:
@@ -341,14 +379,8 @@ def ssl_wrap_socket(
     if ca_certs or ca_cert_dir or ca_cert_data:
         try:
             context.load_verify_locations(ca_certs, ca_cert_dir, ca_cert_data)
-        except IOError as e:  # Platform-specific: Python 2.7
+        except (IOError, OSError) as e:
             raise SSLError(e)
-        # Py33 raises FileNotFoundError which subclasses OSError
-        # These are not equivalent unless we check the errno attribute
-        except OSError as e:  # Platform-specific: Python 3.3 and beyond
-            if e.errno == errno.ENOENT:
-                raise SSLError(e)
-            raise
 
     elif ssl_context is None and hasattr(context, "load_default_certs"):
         # try to load OS default certs; works well on Windows (require Python3.4+)
@@ -366,16 +398,21 @@ def ssl_wrap_socket(
         else:
             context.load_cert_chain(certfile, keyfile, key_password)
 
+    try:
+        if hasattr(context, "set_alpn_protocols"):
+            context.set_alpn_protocols(ALPN_PROTOCOLS)
+    except NotImplementedError:
+        pass
+
     # If we detect server_hostname is an IP address then the SNI
     # extension should not be used according to RFC3546 Section 3.1
-    # We shouldn't warn the user if SNI isn't available but we would
-    # not be using SNI anyways due to IP address for server_hostname.
-    if (
-        server_hostname is not None and not is_ipaddress(server_hostname)
-    ) or IS_SECURETRANSPORT:
-        if HAS_SNI and server_hostname is not None:
-            return context.wrap_socket(sock, server_hostname=server_hostname)
-
+    use_sni_hostname = server_hostname and not is_ipaddress(server_hostname)
+    # SecureTransport uses server_hostname in certificate verification.
+    send_sni = (use_sni_hostname and HAS_SNI) or (
+        IS_SECURETRANSPORT and server_hostname
+    )
+    # Do not warn the user if server_hostname is an invalid SNI hostname.
+    if not HAS_SNI and use_sni_hostname:
         warnings.warn(
             "An HTTPS request has been made, but the SNI (Server Name "
             "Indication) extension to TLS is not available on this platform. "
@@ -387,7 +424,13 @@ def ssl_wrap_socket(
             SNIMissingWarning,
         )
 
-    return context.wrap_socket(sock)
+    if send_sni:
+        ssl_sock = _ssl_wrap_socket_impl(
+            sock, context, tls_in_tls, server_hostname=server_hostname
+        )
+    else:
+        ssl_sock = _ssl_wrap_socket_impl(sock, context, tls_in_tls)
+    return ssl_sock
 
 
 def is_ipaddress(hostname):
@@ -412,3 +455,20 @@ def _is_key_file_encrypted(key_file):
                 return True
 
     return False
+
+
+def _ssl_wrap_socket_impl(sock, ssl_context, tls_in_tls, server_hostname=None):
+    if tls_in_tls:
+        if not SSLTransport:
+            # Import error, ssl is not available.
+            raise ProxySchemeUnsupported(
+                "TLS in TLS requires support for the 'ssl' module"
+            )
+
+        SSLTransport._validate_ssl_context_for_tls_in_tls(ssl_context)
+        return SSLTransport(sock, ssl_context, server_hostname)
+
+    if server_hostname:
+        return ssl_context.wrap_socket(sock, server_hostname=server_hostname)
+    else:
+        return ssl_context.wrap_socket(sock)
diff --git a/src/pip/_vendor/urllib3/util/ssltransport.py b/src/pip/_vendor/urllib3/util/ssltransport.py
new file mode 100644
index 000000000..ca00233c9
--- /dev/null
+++ b/src/pip/_vendor/urllib3/util/ssltransport.py
@@ -0,0 +1,221 @@
+import io
+import socket
+import ssl
+
+from pip._vendor.urllib3.exceptions import ProxySchemeUnsupported
+from pip._vendor.urllib3.packages import six
+
+SSL_BLOCKSIZE = 16384
+
+
+class SSLTransport:
+    """
+    The SSLTransport wraps an existing socket and establishes an SSL connection.
+
+    Contrary to Python's implementation of SSLSocket, it allows you to chain
+    multiple TLS connections together. It's particularly useful if you need to
+    implement TLS within TLS.
+
+    The class supports most of the socket API operations.
+    """
+
+    @staticmethod
+    def _validate_ssl_context_for_tls_in_tls(ssl_context):
+        """
+        Raises a ProxySchemeUnsupported if the provided ssl_context can't be used
+        for TLS in TLS.
+
+        The only requirement is that the ssl_context provides the 'wrap_bio'
+        methods.
+        """
+
+        if not hasattr(ssl_context, "wrap_bio"):
+            if six.PY2:
+                raise ProxySchemeUnsupported(
+                    "TLS in TLS requires SSLContext.wrap_bio() which isn't "
+                    "supported on Python 2"
+                )
+            else:
+                raise ProxySchemeUnsupported(
+                    "TLS in TLS requires SSLContext.wrap_bio() which isn't "
+                    "available on non-native SSLContext"
+                )
+
+    def __init__(
+        self, socket, ssl_context, server_hostname=None, suppress_ragged_eofs=True
+    ):
+        """
+        Create an SSLTransport around socket using the provided ssl_context.
+        """
+        self.incoming = ssl.MemoryBIO()
+        self.outgoing = ssl.MemoryBIO()
+
+        self.suppress_ragged_eofs = suppress_ragged_eofs
+        self.socket = socket
+
+        self.sslobj = ssl_context.wrap_bio(
+            self.incoming, self.outgoing, server_hostname=server_hostname
+        )
+
+        # Perform initial handshake.
+        self._ssl_io_loop(self.sslobj.do_handshake)
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, *_):
+        self.close()
+
+    def fileno(self):
+        return self.socket.fileno()
+
+    def read(self, len=1024, buffer=None):
+        return self._wrap_ssl_read(len, buffer)
+
+    def recv(self, len=1024, flags=0):
+        if flags != 0:
+            raise ValueError("non-zero flags not allowed in calls to recv")
+        return self._wrap_ssl_read(len)
+
+    def recv_into(self, buffer, nbytes=None, flags=0):
+        if flags != 0:
+            raise ValueError("non-zero flags not allowed in calls to recv_into")
+        if buffer and (nbytes is None):
+            nbytes = len(buffer)
+        elif nbytes is None:
+            nbytes = 1024
+        return self.read(nbytes, buffer)
+
+    def sendall(self, data, flags=0):
+        if flags != 0:
+            raise ValueError("non-zero flags not allowed in calls to sendall")
+        count = 0
+        with memoryview(data) as view, view.cast("B") as byte_view:
+            amount = len(byte_view)
+            while count < amount:
+                v = self.send(byte_view[count:])
+                count += v
+
+    def send(self, data, flags=0):
+        if flags != 0:
+            raise ValueError("non-zero flags not allowed in calls to send")
+        response = self._ssl_io_loop(self.sslobj.write, data)
+        return response
+
+    def makefile(
+        self, mode="r", buffering=None, encoding=None, errors=None, newline=None
+    ):
+        """
+        Python's httpclient uses makefile and buffered io when reading HTTP
+        messages and we need to support it.
+
+        This is unfortunately a copy and paste of socket.py makefile with small
+        changes to point to the socket directly.
+        """
+        if not set(mode) <= {"r", "w", "b"}:
+            raise ValueError("invalid mode %r (only r, w, b allowed)" % (mode,))
+
+        writing = "w" in mode
+        reading = "r" in mode or not writing
+        assert reading or writing
+        binary = "b" in mode
+        rawmode = ""
+        if reading:
+            rawmode += "r"
+        if writing:
+            rawmode += "w"
+        raw = socket.SocketIO(self, rawmode)
+        self.socket._io_refs += 1
+        if buffering is None:
+            buffering = -1
+        if buffering < 0:
+            buffering = io.DEFAULT_BUFFER_SIZE
+        if buffering == 0:
+            if not binary:
+                raise ValueError("unbuffered streams must be binary")
+            return raw
+        if reading and writing:
+            buffer = io.BufferedRWPair(raw, raw, buffering)
+        elif reading:
+            buffer = io.BufferedReader(raw, buffering)
+        else:
+            assert writing
+            buffer = io.BufferedWriter(raw, buffering)
+        if binary:
+            return buffer
+        text = io.TextIOWrapper(buffer, encoding, errors, newline)
+        text.mode = mode
+        return text
+
+    def unwrap(self):
+        self._ssl_io_loop(self.sslobj.unwrap)
+
+    def close(self):
+        self.socket.close()
+
+    def getpeercert(self, binary_form=False):
+        return self.sslobj.getpeercert(binary_form)
+
+    def version(self):
+        return self.sslobj.version()
+
+    def cipher(self):
+        return self.sslobj.cipher()
+
+    def selected_alpn_protocol(self):
+        return self.sslobj.selected_alpn_protocol()
+
+    def selected_npn_protocol(self):
+        return self.sslobj.selected_npn_protocol()
+
+    def shared_ciphers(self):
+        return self.sslobj.shared_ciphers()
+
+    def compression(self):
+        return self.sslobj.compression()
+
+    def settimeout(self, value):
+        self.socket.settimeout(value)
+
+    def gettimeout(self):
+        return self.socket.gettimeout()
+
+    def _decref_socketios(self):
+        self.socket._decref_socketios()
+
+    def _wrap_ssl_read(self, len, buffer=None):
+        try:
+            return self._ssl_io_loop(self.sslobj.read, len, buffer)
+        except ssl.SSLError as e:
+            if e.errno == ssl.SSL_ERROR_EOF and self.suppress_ragged_eofs:
+                return 0  # eof, return 0.
+            else:
+                raise
+
+    def _ssl_io_loop(self, func, *args):
+        """ Performs an I/O loop between incoming/outgoing and the socket."""
+        should_loop = True
+        ret = None
+
+        while should_loop:
+            errno = None
+            try:
+                ret = func(*args)
+            except ssl.SSLError as e:
+                if e.errno not in (ssl.SSL_ERROR_WANT_READ, ssl.SSL_ERROR_WANT_WRITE):
+                    # WANT_READ, and WANT_WRITE are expected, others are not.
+                    raise e
+                errno = e.errno
+
+            buf = self.outgoing.read()
+            self.socket.sendall(buf)
+
+            if errno is None:
+                should_loop = False
+            elif errno == ssl.SSL_ERROR_WANT_READ:
+                buf = self.socket.recv(SSL_BLOCKSIZE)
+                if buf:
+                    self.incoming.write(buf)
+                else:
+                    self.incoming.write_eof()
+        return ret
diff --git a/src/pip/_vendor/urllib3/util/timeout.py b/src/pip/_vendor/urllib3/util/timeout.py
index b61fea75c..ff69593b0 100644
--- a/src/pip/_vendor/urllib3/util/timeout.py
+++ b/src/pip/_vendor/urllib3/util/timeout.py
@@ -1,9 +1,10 @@
 from __future__ import absolute_import
 
+import time
+
 # The default socket timeout, used by httplib to indicate that no timeout was
 # specified by the user
 from socket import _GLOBAL_DEFAULT_TIMEOUT
-import time
 
 from ..exceptions import TimeoutStateError
 
@@ -17,22 +18,28 @@ current_time = getattr(time, "monotonic", time.time)
 
 
 class Timeout(object):
-    """ Timeout configuration.
+    """Timeout configuration.
 
-    Timeouts can be defined as a default for a pool::
+    Timeouts can be defined as a default for a pool:
 
-        timeout = Timeout(connect=2.0, read=7.0)
-        http = PoolManager(timeout=timeout)
-        response = http.request('GET', 'http://example.com/')
+    .. code-block:: python
 
-    Or per-request (which overrides the default for the pool)::
+       timeout = Timeout(connect=2.0, read=7.0)
+       http = PoolManager(timeout=timeout)
+       response = http.request('GET', 'http://example.com/')
 
-        response = http.request('GET', 'http://example.com/', timeout=Timeout(10))
+    Or per-request (which overrides the default for the pool):
 
-    Timeouts can be disabled by setting all the parameters to ``None``::
+    .. code-block:: python
 
-        no_timeout = Timeout(connect=None, read=None)
-        response = http.request('GET', 'http://example.com/, timeout=no_timeout)
+       response = http.request('GET', 'http://example.com/', timeout=Timeout(10))
+
+    Timeouts can be disabled by setting all the parameters to ``None``:
+
+    .. code-block:: python
+
+       no_timeout = Timeout(connect=None, read=None)
+       response = http.request('GET', 'http://example.com/, timeout=no_timeout)
 
 
     :param total:
@@ -43,7 +50,7 @@ class Timeout(object):
 
         Defaults to None.
 
-    :type total: integer, float, or None
+    :type total: int, float, or None
 
     :param connect:
         The maximum amount of time (in seconds) to wait for a connection
@@ -53,7 +60,7 @@ class Timeout(object):
         <http://hg.python.org/cpython/file/603b4d593758/Lib/socket.py#l535>`_.
         None will set an infinite timeout for connection attempts.
 
-    :type connect: integer, float, or None
+    :type connect: int, float, or None
 
     :param read:
         The maximum amount of time (in seconds) to wait between consecutive
@@ -63,7 +70,7 @@ class Timeout(object):
         <http://hg.python.org/cpython/file/603b4d593758/Lib/socket.py#l535>`_.
         None will set an infinite timeout.
 
-    :type read: integer, float, or None
+    :type read: int, float, or None
 
     .. note::
 
@@ -111,7 +118,7 @@ class Timeout(object):
 
     @classmethod
     def _validate_timeout(cls, value, name):
-        """ Check that a timeout attribute is valid.
+        """Check that a timeout attribute is valid.
 
         :param value: The timeout value to validate
         :param name: The name of the timeout attribute to validate. This is
@@ -157,7 +164,7 @@ class Timeout(object):
 
     @classmethod
     def from_float(cls, timeout):
-        """ Create a new Timeout from a legacy timeout value.
+        """Create a new Timeout from a legacy timeout value.
 
         The timeout value used by httplib.py sets the same timeout on the
         connect(), and recv() socket requests. This creates a :class:`Timeout`
@@ -172,7 +179,7 @@ class Timeout(object):
         return Timeout(read=timeout, connect=timeout)
 
     def clone(self):
-        """ Create a copy of the timeout object
+        """Create a copy of the timeout object
 
         Timeout properties are stored per-pool but each request needs a fresh
         Timeout object to ensure each one has its own start/stop configured.
@@ -186,7 +193,7 @@ class Timeout(object):
         return Timeout(connect=self._connect, read=self._read, total=self.total)
 
     def start_connect(self):
-        """ Start the timeout clock, used during a connect() attempt
+        """Start the timeout clock, used during a connect() attempt
 
         :raises urllib3.exceptions.TimeoutStateError: if you attempt
             to start a timer that has been started already.
@@ -197,7 +204,7 @@ class Timeout(object):
         return self._start_connect
 
     def get_connect_duration(self):
-        """ Gets the time elapsed since the call to :meth:`start_connect`.
+        """Gets the time elapsed since the call to :meth:`start_connect`.
 
         :return: Elapsed time in seconds.
         :rtype: float
@@ -212,7 +219,7 @@ class Timeout(object):
 
     @property
     def connect_timeout(self):
-        """ Get the value to use when setting a connection timeout.
+        """Get the value to use when setting a connection timeout.
 
         This will be a positive float or integer, the value None
         (never timeout), or the default system timeout.
@@ -230,7 +237,7 @@ class Timeout(object):
 
     @property
     def read_timeout(self):
-        """ Get the value for the read timeout.
+        """Get the value for the read timeout.
 
         This assumes some time has elapsed in the connection timeout and
         computes the read timeout appropriately.
diff --git a/src/pip/_vendor/urllib3/util/url.py b/src/pip/_vendor/urllib3/util/url.py
index 0eb0b6a8c..66c8795b1 100644
--- a/src/pip/_vendor/urllib3/util/url.py
+++ b/src/pip/_vendor/urllib3/util/url.py
@@ -1,11 +1,11 @@
 from __future__ import absolute_import
+
 import re
 from collections import namedtuple
 
 from ..exceptions import LocationParseError
 from ..packages import six
 
-
 url_attrs = ["scheme", "auth", "host", "port", "path", "query", "fragment"]
 
 # We only want to normalize urls with an HTTP(S) scheme.
diff --git a/src/pip/_vendor/urllib3/util/wait.py b/src/pip/_vendor/urllib3/util/wait.py
index d71d2fd72..c280646c7 100644
--- a/src/pip/_vendor/urllib3/util/wait.py
+++ b/src/pip/_vendor/urllib3/util/wait.py
@@ -1,7 +1,7 @@
 import errno
-from functools import partial
 import select
 import sys
+from functools import partial
 
 try:
     from time import monotonic
@@ -140,14 +140,14 @@ def wait_for_socket(*args, **kwargs):
 
 
 def wait_for_read(sock, timeout=None):
-    """ Waits for reading to be available on a given socket.
+    """Waits for reading to be available on a given socket.
     Returns True if the socket is readable, or False if the timeout expired.
     """
     return wait_for_socket(sock, read=True, timeout=timeout)
 
 
 def wait_for_write(sock, timeout=None):
-    """ Waits for writing to be available on a given socket.
+    """Waits for writing to be available on a given socket.
     Returns True if the socket is readable, or False if the timeout expired.
     """
     return wait_for_socket(sock, write=True, timeout=timeout)
diff --git a/src/pip/_vendor/vendor.txt b/src/pip/_vendor/vendor.txt
index f08348b9f..5943f971d 100644
--- a/src/pip/_vendor/vendor.txt
+++ b/src/pip/_vendor/vendor.txt
@@ -15,7 +15,7 @@ requests==2.25.0
     certifi==2020.11.8
     chardet==3.0.4
     idna==2.10
-    urllib3==1.25.9
+    urllib3==1.26.2
 resolvelib==0.4.0
 retrying==1.3.3
 setuptools==44.0.0