From 1471897b84b43c467c753b5edebe636f835afc6a Mon Sep 17 00:00:00 2001
From: Devesh Kumar Singh <deveshkusingh@gmail.com>
Date: Fri, 3 Apr 2020 13:08:41 +0530
Subject: [PATCH 1/6] Improve check for svn version string

---
 news/7968.bugfix                    |  1 +
 src/pip/_internal/vcs/subversion.py | 15 +++++++++++++--
 tests/unit/test_vcs.py              | 12 ++++++++++++
 3 files changed, 26 insertions(+), 2 deletions(-)
 create mode 100644 news/7968.bugfix

diff --git a/news/7968.bugfix b/news/7968.bugfix
new file mode 100644
index 000000000..d6959730a
--- /dev/null
+++ b/news/7968.bugfix
@@ -0,0 +1 @@
+Look for version string in the entire output of svn --version, not just the first line
diff --git a/src/pip/_internal/vcs/subversion.py b/src/pip/_internal/vcs/subversion.py
index 0ec659744..d0fe3cd9d 100644
--- a/src/pip/_internal/vcs/subversion.py
+++ b/src/pip/_internal/vcs/subversion.py
@@ -25,7 +25,7 @@ _svn_info_xml_url_re = re.compile(r'<url>(.*)</url>')
 
 
 if MYPY_CHECK_RUNNING:
-    from typing import Optional, Tuple
+    from typing import Optional, Tuple, Text
     from pip._internal.utils.subprocess import CommandArgs
     from pip._internal.utils.misc import HiddenText
     from pip._internal.vcs.versioncontrol import AuthInfo, RevOptions
@@ -215,7 +215,18 @@ class Subversion(VersionControl):
         #   svn, version 1.7.14 (r1542130)
         #      compiled Mar 28 2018, 08:49:13 on x86_64-pc-linux-gnu
         version_prefix = 'svn, version '
-        version = self.run_command(['--version'], show_stdout=False)
+        cmd_output = self.run_command(['--version'], show_stdout=False)
+
+        # Split the output by newline, and find the first line where
+        # version_prefix is present
+        output_lines = cmd_output.split('\n')
+        version = ''  # type: Text
+
+        for line in output_lines:
+            if version_prefix in line:
+                version = line
+                break
+
         if not version.startswith(version_prefix):
             return ()
 
diff --git a/tests/unit/test_vcs.py b/tests/unit/test_vcs.py
index 590cb5c0b..166585db3 100644
--- a/tests/unit/test_vcs.py
+++ b/tests/unit/test_vcs.py
@@ -443,6 +443,18 @@ def test_subversion__call_vcs_version():
     ('svn, version 1.10.3 (r1842928)\n'
      '   compiled Feb 25 2019, 14:20:39 on x86_64-apple-darwin17.0.0',
      (1, 10, 3)),
+    ('Warning: Failed to set locale category LC_NUMERIC to en_IN.\n'
+     'Warning: Failed to set locale category LC_TIME to en_IN.\n'
+     'svn, version 1.10.3 (r1842928)\n'
+     '   compiled Feb 25 2019, 14:20:39 on x86_64-apple-darwin17.0.0',
+     (1, 10, 3)),
+    ('Warning: Failed to set locale category LC_NUMERIC to en_IN.\n'
+     'Warning: Failed to set locale category LC_TIME to en_IN.\n'
+     'svn, version 1.10.3 (r1842928)\n'
+     '   compiled Feb 25 2019, 14:20:39 on x86_64-apple-darwin17.0.0'
+     'svn, version 1.11.3 (r1842928)\n'
+     '   compiled Feb 25 2019, 14:20:39 on x86_64-apple-darwin17.0.0',
+     (1, 10, 3)),
     ('svn, version 1.9.7 (r1800392)', (1, 9, 7)),
     ('svn, version 1.9.7a1 (r1800392)', ()),
     ('svn, version 1.9 (r1800392)', (1, 9)),

From 8adbc216a647b6b349f1b7f1eaa9e71cd3108955 Mon Sep 17 00:00:00 2001
From: Devesh Kumar Singh <deveshkusingh@gmail.com>
Date: Sat, 18 Apr 2020 12:47:35 +0530
Subject: [PATCH 2/6] Create call_subprocess just for vcs commands

---
 src/pip/_internal/exceptions.py         |   5 +
 src/pip/_internal/vcs/subversion.py     |  14 +--
 src/pip/_internal/vcs/versioncontrol.py | 144 ++++++++++++++++++++++--
 tests/unit/test_vcs.py                  |  12 --
 4 files changed, 139 insertions(+), 36 deletions(-)

diff --git a/src/pip/_internal/exceptions.py b/src/pip/_internal/exceptions.py
index 8ac85485e..e0d7f095d 100644
--- a/src/pip/_internal/exceptions.py
+++ b/src/pip/_internal/exceptions.py
@@ -84,6 +84,11 @@ class CommandError(PipError):
     """Raised when there is an error in command-line arguments"""
 
 
+class SubProcessError(PipError):
+    """Raised when there is an error raised while executing a
+    command in subprocess"""
+
+
 class PreviousBuildDirError(PipError):
     """Raised when there's a previous conflicting build directory"""
 
diff --git a/src/pip/_internal/vcs/subversion.py b/src/pip/_internal/vcs/subversion.py
index d0fe3cd9d..3f9d0833f 100644
--- a/src/pip/_internal/vcs/subversion.py
+++ b/src/pip/_internal/vcs/subversion.py
@@ -25,7 +25,7 @@ _svn_info_xml_url_re = re.compile(r'<url>(.*)</url>')
 
 
 if MYPY_CHECK_RUNNING:
-    from typing import Optional, Tuple, Text
+    from typing import Optional, Tuple
     from pip._internal.utils.subprocess import CommandArgs
     from pip._internal.utils.misc import HiddenText
     from pip._internal.vcs.versioncontrol import AuthInfo, RevOptions
@@ -215,17 +215,7 @@ class Subversion(VersionControl):
         #   svn, version 1.7.14 (r1542130)
         #      compiled Mar 28 2018, 08:49:13 on x86_64-pc-linux-gnu
         version_prefix = 'svn, version '
-        cmd_output = self.run_command(['--version'], show_stdout=False)
-
-        # Split the output by newline, and find the first line where
-        # version_prefix is present
-        output_lines = cmd_output.split('\n')
-        version = ''  # type: Text
-
-        for line in output_lines:
-            if version_prefix in line:
-                version = line
-                break
+        version = self.run_command(['--version'], show_stdout=True)
 
         if not version.startswith(version_prefix):
             return ()
diff --git a/src/pip/_internal/vcs/versioncontrol.py b/src/pip/_internal/vcs/versioncontrol.py
index 71b4650a2..1956559b3 100644
--- a/src/pip/_internal/vcs/versioncontrol.py
+++ b/src/pip/_internal/vcs/versioncontrol.py
@@ -6,13 +6,19 @@ import errno
 import logging
 import os
 import shutil
+import subprocess
 import sys
 
 from pip._vendor import pkg_resources
 from pip._vendor.six.moves.urllib import parse as urllib_parse
 
-from pip._internal.exceptions import BadCommand, InstallationError
-from pip._internal.utils.compat import samefile
+from pip._internal.exceptions import (
+    BadCommand,
+    InstallationError,
+    SubProcessError,
+)
+from pip._internal.utils.compat import console_to_str, samefile
+from pip._internal.utils.logging import subprocess_logger
 from pip._internal.utils.misc import (
     ask_path_exists,
     backup_dir,
@@ -21,16 +27,20 @@ from pip._internal.utils.misc import (
     hide_value,
     rmtree,
 )
-from pip._internal.utils.subprocess import call_subprocess, make_command
+from pip._internal.utils.subprocess import (
+    format_command_args,
+    make_command,
+    make_subprocess_output_error,
+    reveal_command_args,
+)
 from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 from pip._internal.utils.urls import get_url_scheme
 
 if MYPY_CHECK_RUNNING:
     from typing import (
-        Any, Dict, Iterable, Iterator, List, Mapping, Optional, Text, Tuple,
+        Dict, Iterable, Iterator, List, Optional, Text, Tuple,
         Type, Union
     )
-    from pip._internal.cli.spinners import SpinnerInterface
     from pip._internal.utils.misc import HiddenText
     from pip._internal.utils.subprocess import CommandArgs
 
@@ -71,6 +81,123 @@ def make_vcs_requirement_url(repo_url, rev, project_name, subdir=None):
     return req
 
 
+def call_subprocess(
+    cmd,  # type: Union[List[str], CommandArgs]
+    show_stdout=False,  # type: bool
+    cwd=None,  # type: Optional[str]
+    on_returncode='raise',  # type: str
+    extra_ok_returncodes=None,  # type: Optional[Iterable[int]]
+    log_failed_cmd=True  # type: Optional[bool]
+):
+    # type: (...) -> Text
+    """
+    Args:
+      show_stdout: if true, use INFO to log the subprocess's stderr and
+        stdout streams.  Otherwise, use DEBUG.  Defaults to False.
+      extra_ok_returncodes: an iterable of integer return codes that are
+        acceptable, in addition to 0. Defaults to None, which means [].
+      log_failed_cmd: if false, failed commands are not logged,
+        only raised.
+    """
+    if extra_ok_returncodes is None:
+        extra_ok_returncodes = []
+    # Most places in pip use show_stdout=False.
+    # What this means is--
+    #
+    # - We log this output of stdout and stderr at DEBUG level
+    # as it is received.
+    # - If DEBUG logging isn't enabled (e.g. if --verbose logging wasn't
+    #   requested), then we show a spinner so the user can still see the
+    #   subprocess is in progress.
+    # - If the subprocess exits with an error, we log the output to stderr
+    #   at ERROR level if it hasn't already been displayed to the console
+    #   (e.g. if --verbose logging wasn't enabled).  This way we don't log
+    #   the output to the console twice.
+    #
+    # If show_stdout=True, then the above is still done, but with DEBUG
+    # replaced by INFO.
+    if show_stdout:
+        # Then log the subprocess output at INFO level.
+        log_subprocess = subprocess_logger.info
+        used_level = logging.INFO
+    else:
+        # Then log the subprocess output using DEBUG.  This also ensures
+        # it will be logged to the log file (aka user_log), if enabled.
+        log_subprocess = subprocess_logger.debug
+        used_level = logging.DEBUG
+
+    # Whether the subprocess will be visible in the console.
+    showing_subprocess = subprocess_logger.getEffectiveLevel() <= used_level
+
+    command_desc = format_command_args(cmd)
+    try:
+        proc = subprocess.Popen(
+            # Convert HiddenText objects to the underlying str.
+            reveal_command_args(cmd),
+            stdout=subprocess.PIPE,
+            stderr=subprocess.PIPE,
+            cwd=cwd
+        )
+        if proc.stdin:
+            proc.stdin.close()
+    except Exception as exc:
+        if log_failed_cmd:
+            subprocess_logger.critical(
+                "Error %s while executing command %s", exc, command_desc,
+            )
+        raise
+    all_output = []
+    while True:
+        # The "line" value is a unicode string in Python 2.
+        line = None
+        if proc.stdout:
+            line = console_to_str(proc.stdout.readline())
+        if not line:
+            break
+        line = line.rstrip()
+        all_output.append(line + '\n')
+
+        # Show the line immediately.
+        log_subprocess(line)
+    try:
+        proc.wait()
+    finally:
+        if proc.stdout:
+            proc.stdout.close()
+
+    proc_had_error = (
+        proc.returncode and proc.returncode not in extra_ok_returncodes
+    )
+    if proc_had_error:
+        if on_returncode == 'raise':
+            if not showing_subprocess and log_failed_cmd:
+                # Then the subprocess streams haven't been logged to the
+                # console yet.
+                msg = make_subprocess_output_error(
+                    cmd_args=cmd,
+                    cwd=cwd,
+                    lines=all_output,
+                    exit_status=proc.returncode,
+                )
+                subprocess_logger.error(msg)
+            exc_msg = (
+                'Command errored out with exit status {}: {} '
+                'Check the logs for full command output.'
+            ).format(proc.returncode, command_desc)
+            raise SubProcessError(exc_msg)
+        elif on_returncode == 'warn':
+            subprocess_logger.warning(
+                'Command "{}" had error code {} in {}'.format(
+                    command_desc, proc.returncode, cwd)
+            )
+        elif on_returncode == 'ignore':
+            pass
+        else:
+            raise ValueError('Invalid value: on_returncode={!r}'.format(
+                             on_returncode))
+    return ''.join(all_output)
+
+
 def find_path_to_setup_from_repo_root(location, repo_root):
     # type: (str, str) -> Optional[str]
     """
@@ -663,9 +790,6 @@ class VersionControl(object):
         cwd=None,  # type: Optional[str]
         on_returncode='raise',  # type: str
         extra_ok_returncodes=None,  # type: Optional[Iterable[int]]
-        command_desc=None,  # type: Optional[str]
-        extra_environ=None,  # type: Optional[Mapping[str, Any]]
-        spinner=None,  # type: Optional[SpinnerInterface]
         log_failed_cmd=True  # type: bool
     ):
         # type: (...) -> Text
@@ -679,10 +803,6 @@ class VersionControl(object):
             return call_subprocess(cmd, show_stdout, cwd,
                                    on_returncode=on_returncode,
                                    extra_ok_returncodes=extra_ok_returncodes,
-                                   command_desc=command_desc,
-                                   extra_environ=extra_environ,
-                                   unset_environ=cls.unset_environ,
-                                   spinner=spinner,
                                    log_failed_cmd=log_failed_cmd)
         except OSError as e:
             # errno.ENOENT = no such file or directory
diff --git a/tests/unit/test_vcs.py b/tests/unit/test_vcs.py
index 166585db3..590cb5c0b 100644
--- a/tests/unit/test_vcs.py
+++ b/tests/unit/test_vcs.py
@@ -443,18 +443,6 @@ def test_subversion__call_vcs_version():
     ('svn, version 1.10.3 (r1842928)\n'
      '   compiled Feb 25 2019, 14:20:39 on x86_64-apple-darwin17.0.0',
      (1, 10, 3)),
-    ('Warning: Failed to set locale category LC_NUMERIC to en_IN.\n'
-     'Warning: Failed to set locale category LC_TIME to en_IN.\n'
-     'svn, version 1.10.3 (r1842928)\n'
-     '   compiled Feb 25 2019, 14:20:39 on x86_64-apple-darwin17.0.0',
-     (1, 10, 3)),
-    ('Warning: Failed to set locale category LC_NUMERIC to en_IN.\n'
-     'Warning: Failed to set locale category LC_TIME to en_IN.\n'
-     'svn, version 1.10.3 (r1842928)\n'
-     '   compiled Feb 25 2019, 14:20:39 on x86_64-apple-darwin17.0.0'
-     'svn, version 1.11.3 (r1842928)\n'
-     '   compiled Feb 25 2019, 14:20:39 on x86_64-apple-darwin17.0.0',
-     (1, 10, 3)),
     ('svn, version 1.9.7 (r1800392)', (1, 9, 7)),
     ('svn, version 1.9.7a1 (r1800392)', ()),
     ('svn, version 1.9 (r1800392)', (1, 9)),

From 94882fd1ed9171ea5a2f4b8904dbd8763f05ba68 Mon Sep 17 00:00:00 2001
From: Devesh Kumar Singh <deveshkusingh@gmail.com>
Date: Sat, 18 Apr 2020 14:10:45 +0530
Subject: [PATCH 3/6] Remove show_stdout from run_command args

---
 src/pip/_internal/vcs/bazaar.py         |  7 ++--
 src/pip/_internal/vcs/git.py            | 19 +++++------
 src/pip/_internal/vcs/mercurial.py      | 16 ++++-----
 src/pip/_internal/vcs/subversion.py     |  9 +++--
 src/pip/_internal/vcs/versioncontrol.py | 44 ++++++++-----------------
 5 files changed, 36 insertions(+), 59 deletions(-)

diff --git a/src/pip/_internal/vcs/bazaar.py b/src/pip/_internal/vcs/bazaar.py
index 347c06f9d..94408c52f 100644
--- a/src/pip/_internal/vcs/bazaar.py
+++ b/src/pip/_internal/vcs/bazaar.py
@@ -54,8 +54,7 @@ class Bazaar(VersionControl):
 
         url, rev_options = self.get_url_rev_options(url)
         self.run_command(
-            make_command('export', location, url, rev_options.to_args()),
-            show_stdout=False,
+            make_command('export', location, url, rev_options.to_args())
         )
 
     def fetch_new(self, dest, url, rev_options):
@@ -92,7 +91,7 @@ class Bazaar(VersionControl):
 
     @classmethod
     def get_remote_url(cls, location):
-        urls = cls.run_command(['info'], show_stdout=False, cwd=location)
+        urls = cls.run_command(['info'], cwd=location)
         for line in urls.splitlines():
             line = line.strip()
             for x in ('checkout of branch: ',
@@ -107,7 +106,7 @@ class Bazaar(VersionControl):
     @classmethod
     def get_revision(cls, location):
         revision = cls.run_command(
-            ['revno'], show_stdout=False, cwd=location,
+            ['revno'], cwd=location,
         )
         return revision.splitlines()[-1]
 
diff --git a/src/pip/_internal/vcs/git.py b/src/pip/_internal/vcs/git.py
index e173ec894..61d0ff647 100644
--- a/src/pip/_internal/vcs/git.py
+++ b/src/pip/_internal/vcs/git.py
@@ -11,7 +11,7 @@ from pip._vendor.packaging.version import parse as parse_version
 from pip._vendor.six.moves.urllib import parse as urllib_parse
 from pip._vendor.six.moves.urllib import request as urllib_request
 
-from pip._internal.exceptions import BadCommand, InstallationError
+from pip._internal.exceptions import BadCommand, SubProcessError
 from pip._internal.utils.misc import display_path, hide_url
 from pip._internal.utils.subprocess import make_command
 from pip._internal.utils.temp_dir import TempDirectory
@@ -78,7 +78,7 @@ class Git(VersionControl):
 
     def get_git_version(self):
         VERSION_PFX = 'git version '
-        version = self.run_command(['version'], show_stdout=False)
+        version = self.run_command(['version'])
         if version.startswith(VERSION_PFX):
             version = version[len(VERSION_PFX):].split()[0]
         else:
@@ -101,7 +101,7 @@ class Git(VersionControl):
         # and to suppress the message to stderr.
         args = ['symbolic-ref', '-q', 'HEAD']
         output = cls.run_command(
-            args, extra_ok_returncodes=(1, ), show_stdout=False, cwd=location,
+            args, extra_ok_returncodes=(1, ), cwd=location,
         )
         ref = output.strip()
 
@@ -120,7 +120,7 @@ class Git(VersionControl):
             self.unpack(temp_dir.path, url=url)
             self.run_command(
                 ['checkout-index', '-a', '-f', '--prefix', location],
-                show_stdout=False, cwd=temp_dir.path
+                cwd=temp_dir.path
             )
 
     @classmethod
@@ -135,7 +135,7 @@ class Git(VersionControl):
         """
         # Pass rev to pre-filter the list.
         output = cls.run_command(['show-ref', rev], cwd=dest,
-                                 show_stdout=False, on_returncode='ignore')
+                                 on_returncode='ignore')
         refs = {}
         for line in output.strip().splitlines():
             try:
@@ -286,7 +286,7 @@ class Git(VersionControl):
         # exits with return code 1 if there are no matching lines.
         stdout = cls.run_command(
             ['config', '--get-regexp', r'remote\..*\.url'],
-            extra_ok_returncodes=(1, ), show_stdout=False, cwd=location,
+            extra_ok_returncodes=(1, ), cwd=location,
         )
         remotes = stdout.splitlines()
         try:
@@ -306,7 +306,7 @@ class Git(VersionControl):
         if rev is None:
             rev = 'HEAD'
         current_rev = cls.run_command(
-            ['rev-parse', rev], show_stdout=False, cwd=location,
+            ['rev-parse', rev], cwd=location,
         )
         return current_rev.strip()
 
@@ -319,7 +319,7 @@ class Git(VersionControl):
         # find the repo root
         git_dir = cls.run_command(
             ['rev-parse', '--git-dir'],
-            show_stdout=False, cwd=location).strip()
+            cwd=location).strip()
         if not os.path.isabs(git_dir):
             git_dir = os.path.join(location, git_dir)
         repo_root = os.path.abspath(os.path.join(git_dir, '..'))
@@ -378,7 +378,6 @@ class Git(VersionControl):
             r = cls.run_command(
                 ['rev-parse', '--show-toplevel'],
                 cwd=location,
-                show_stdout=False,
                 on_returncode='raise',
                 log_failed_cmd=False,
             )
@@ -386,7 +385,7 @@ class Git(VersionControl):
             logger.debug("could not determine if %s is under git control "
                          "because git is not available", location)
             return None
-        except InstallationError:
+        except SubProcessError:
             return None
         return os.path.normpath(r.rstrip('\r\n'))
 
diff --git a/src/pip/_internal/vcs/mercurial.py b/src/pip/_internal/vcs/mercurial.py
index 75e903cc8..b7f8073fd 100644
--- a/src/pip/_internal/vcs/mercurial.py
+++ b/src/pip/_internal/vcs/mercurial.py
@@ -8,7 +8,7 @@ import os
 
 from pip._vendor.six.moves import configparser
 
-from pip._internal.exceptions import BadCommand, InstallationError
+from pip._internal.exceptions import BadCommand, SubProcessError
 from pip._internal.utils.misc import display_path
 from pip._internal.utils.subprocess import make_command
 from pip._internal.utils.temp_dir import TempDirectory
@@ -47,7 +47,7 @@ class Mercurial(VersionControl):
             self.unpack(temp_dir.path, url=url)
 
             self.run_command(
-                ['archive', location], show_stdout=False, cwd=temp_dir.path
+                ['archive', location], cwd=temp_dir.path
             )
 
     def fetch_new(self, dest, url, rev_options):
@@ -92,7 +92,7 @@ class Mercurial(VersionControl):
     def get_remote_url(cls, location):
         url = cls.run_command(
             ['showconfig', 'paths.default'],
-            show_stdout=False, cwd=location).strip()
+            cwd=location).strip()
         if cls._is_local_repository(url):
             url = path_to_url(url)
         return url.strip()
@@ -103,8 +103,7 @@ class Mercurial(VersionControl):
         Return the repository-local changeset revision number, as an integer.
         """
         current_revision = cls.run_command(
-            ['parents', '--template={rev}'],
-            show_stdout=False, cwd=location).strip()
+            ['parents', '--template={rev}'], cwd=location).strip()
         return current_revision
 
     @classmethod
@@ -115,7 +114,7 @@ class Mercurial(VersionControl):
         """
         current_rev_hash = cls.run_command(
             ['parents', '--template={node}'],
-            show_stdout=False, cwd=location).strip()
+            cwd=location).strip()
         return current_rev_hash
 
     @classmethod
@@ -131,7 +130,7 @@ class Mercurial(VersionControl):
         """
         # find the repo root
         repo_root = cls.run_command(
-            ['root'], show_stdout=False, cwd=location).strip()
+            ['root'], cwd=location).strip()
         if not os.path.isabs(repo_root):
             repo_root = os.path.abspath(os.path.join(location, repo_root))
         return find_path_to_setup_from_repo_root(location, repo_root)
@@ -145,7 +144,6 @@ class Mercurial(VersionControl):
             r = cls.run_command(
                 ['root'],
                 cwd=location,
-                show_stdout=False,
                 on_returncode='raise',
                 log_failed_cmd=False,
             )
@@ -153,7 +151,7 @@ class Mercurial(VersionControl):
             logger.debug("could not determine if %s is under hg control "
                          "because hg is not available", location)
             return None
-        except InstallationError:
+        except SubProcessError:
             return None
         return os.path.normpath(r.rstrip('\r\n'))
 
diff --git a/src/pip/_internal/vcs/subversion.py b/src/pip/_internal/vcs/subversion.py
index 3f9d0833f..4324a5d9f 100644
--- a/src/pip/_internal/vcs/subversion.py
+++ b/src/pip/_internal/vcs/subversion.py
@@ -132,7 +132,7 @@ class Subversion(VersionControl):
 
     @classmethod
     def _get_svn_url_rev(cls, location):
-        from pip._internal.exceptions import InstallationError
+        from pip._internal.exceptions import SubProcessError
 
         entries_path = os.path.join(location, cls.dirname, 'entries')
         if os.path.exists(entries_path):
@@ -165,13 +165,12 @@ class Subversion(VersionControl):
                 # are only potentially needed for remote server requests.
                 xml = cls.run_command(
                     ['info', '--xml', location],
-                    show_stdout=False,
                 )
                 url = _svn_info_xml_url_re.search(xml).group(1)
                 revs = [
                     int(m.group(1)) for m in _svn_info_xml_rev_re.finditer(xml)
                 ]
-            except InstallationError:
+            except SubProcessError:
                 url, revs = None, []
 
         if revs:
@@ -215,7 +214,7 @@ class Subversion(VersionControl):
         #   svn, version 1.7.14 (r1542130)
         #      compiled Mar 28 2018, 08:49:13 on x86_64-pc-linux-gnu
         version_prefix = 'svn, version '
-        version = self.run_command(['--version'], show_stdout=True)
+        version = self.run_command(['--version'])
 
         if not version.startswith(version_prefix):
             return ()
@@ -298,7 +297,7 @@ class Subversion(VersionControl):
                 'export', self.get_remote_call_options(),
                 rev_options.to_args(), url, location,
             )
-            self.run_command(cmd_args, show_stdout=False)
+            self.run_command(cmd_args)
 
     def fetch_new(self, dest, url, rev_options):
         # type: (str, HiddenText, RevOptions) -> None
diff --git a/src/pip/_internal/vcs/versioncontrol.py b/src/pip/_internal/vcs/versioncontrol.py
index 1956559b3..02bdda37c 100644
--- a/src/pip/_internal/vcs/versioncontrol.py
+++ b/src/pip/_internal/vcs/versioncontrol.py
@@ -39,7 +39,7 @@ from pip._internal.utils.urls import get_url_scheme
 if MYPY_CHECK_RUNNING:
     from typing import (
         Dict, Iterable, Iterator, List, Optional, Text, Tuple,
-        Type, Union
+        Type, Union, Mapping, Any
     )
     from pip._internal.utils.misc import HiddenText
     from pip._internal.utils.subprocess import CommandArgs
@@ -83,17 +83,15 @@ def make_vcs_requirement_url(repo_url, rev, project_name, subdir=None):
 
 def call_subprocess(
     cmd,  # type: Union[List[str], CommandArgs]
-    show_stdout=False,  # type: bool
     cwd=None,  # type: Optional[str]
     on_returncode='raise',  # type: str
+    extra_environ=None,  # type: Optional[Mapping[str, Any]]
     extra_ok_returncodes=None,  # type: Optional[Iterable[int]]
     log_failed_cmd=True  # type: Optional[bool]
 ):
     # type: (...) -> Text
     """
     Args:
-      show_stdout: if true, use INFO to log the subprocess's stderr and
-        stdout streams.  Otherwise, use DEBUG.  Defaults to False.
       extra_ok_returncodes: an iterable of integer return codes that are
         acceptable, in addition to 0. Defaults to None, which means [].
       log_failed_cmd: if false, failed commands are not logged,
@@ -101,33 +99,16 @@ def call_subprocess(
     """
     if extra_ok_returncodes is None:
         extra_ok_returncodes = []
-    # Most places in pip use show_stdout=False.
-    # What this means is--
-    #
-    # - We log this output of stdout and stderr at DEBUG level
-    # as it is received.
-    # - If DEBUG logging isn't enabled (e.g. if --verbose logging wasn't
-    #   requested), then we show a spinner so the user can still see the
-    #   subprocess is in progress.
-    # - If the subprocess exits with an error, we log the output to stderr
-    #   at ERROR level if it hasn't already been displayed to the console
-    #   (e.g. if --verbose logging wasn't enabled).  This way we don't log
-    #   the output to the console twice.
-    #
-    # If show_stdout=True, then the above is still done, but with DEBUG
-    # replaced by INFO.
-    if show_stdout:
-        # Then log the subprocess output at INFO level.
-        log_subprocess = subprocess_logger.info
-        used_level = logging.INFO
-    else:
-        # Then log the subprocess output using DEBUG.  This also ensures
-        # it will be logged to the log file (aka user_log), if enabled.
-        log_subprocess = subprocess_logger.debug
-        used_level = logging.DEBUG
+
+    # log the subprocess output at DEBUG level.
+    log_subprocess = subprocess_logger.debug
+
+    env = os.environ.copy()
+    if extra_environ:
+        env.update(extra_environ)
 
     # Whether the subprocess will be visible in the console.
-    showing_subprocess = subprocess_logger.getEffectiveLevel() <= used_level
+    showing_subprocess = True
 
     command_desc = format_command_args(cmd)
     try:
@@ -786,9 +767,9 @@ class VersionControl(object):
     def run_command(
         cls,
         cmd,  # type: Union[List[str], CommandArgs]
-        show_stdout=True,  # type: bool
         cwd=None,  # type: Optional[str]
         on_returncode='raise',  # type: str
+        extra_environ=None,  # type: Optional[Mapping[str, Any]]
         extra_ok_returncodes=None,  # type: Optional[Iterable[int]]
         log_failed_cmd=True  # type: bool
     ):
@@ -800,8 +781,9 @@ class VersionControl(object):
         """
         cmd = make_command(cls.name, *cmd)
         try:
-            return call_subprocess(cmd, show_stdout, cwd,
+            return call_subprocess(cmd, cwd,
                                    on_returncode=on_returncode,
+                                   extra_environ=extra_environ,
                                    extra_ok_returncodes=extra_ok_returncodes,
                                    log_failed_cmd=log_failed_cmd)
         except OSError as e:

From ab3ee7191ca47294f8827916180969e23f5e0381 Mon Sep 17 00:00:00 2001
From: Devesh Kumar Singh <deveshkusingh@gmail.com>
Date: Thu, 14 May 2020 20:06:36 +0530
Subject: [PATCH 4/6] Remove on_returncode parameter from call_subprocess

---
 src/pip/_internal/vcs/git.py            | 10 ++++--
 src/pip/_internal/vcs/mercurial.py      |  1 -
 src/pip/_internal/vcs/versioncontrol.py | 42 +++++++++----------------
 3 files changed, 21 insertions(+), 32 deletions(-)

diff --git a/src/pip/_internal/vcs/git.py b/src/pip/_internal/vcs/git.py
index 61d0ff647..a9c7fb66e 100644
--- a/src/pip/_internal/vcs/git.py
+++ b/src/pip/_internal/vcs/git.py
@@ -134,8 +134,13 @@ class Git(VersionControl):
           rev: the revision name.
         """
         # Pass rev to pre-filter the list.
-        output = cls.run_command(['show-ref', rev], cwd=dest,
-                                 on_returncode='ignore')
+
+        output = ''
+        try:
+            output = cls.run_command(['show-ref', rev], cwd=dest)
+        except SubProcessError:
+            pass
+
         refs = {}
         for line in output.strip().splitlines():
             try:
@@ -378,7 +383,6 @@ class Git(VersionControl):
             r = cls.run_command(
                 ['rev-parse', '--show-toplevel'],
                 cwd=location,
-                on_returncode='raise',
                 log_failed_cmd=False,
             )
         except BadCommand:
diff --git a/src/pip/_internal/vcs/mercurial.py b/src/pip/_internal/vcs/mercurial.py
index b7f8073fd..69763feae 100644
--- a/src/pip/_internal/vcs/mercurial.py
+++ b/src/pip/_internal/vcs/mercurial.py
@@ -144,7 +144,6 @@ class Mercurial(VersionControl):
             r = cls.run_command(
                 ['root'],
                 cwd=location,
-                on_returncode='raise',
                 log_failed_cmd=False,
             )
         except BadCommand:
diff --git a/src/pip/_internal/vcs/versioncontrol.py b/src/pip/_internal/vcs/versioncontrol.py
index 02bdda37c..96f830f99 100644
--- a/src/pip/_internal/vcs/versioncontrol.py
+++ b/src/pip/_internal/vcs/versioncontrol.py
@@ -84,7 +84,6 @@ def make_vcs_requirement_url(repo_url, rev, project_name, subdir=None):
 def call_subprocess(
     cmd,  # type: Union[List[str], CommandArgs]
     cwd=None,  # type: Optional[str]
-    on_returncode='raise',  # type: str
     extra_environ=None,  # type: Optional[Mapping[str, Any]]
     extra_ok_returncodes=None,  # type: Optional[Iterable[int]]
     log_failed_cmd=True  # type: Optional[bool]
@@ -150,32 +149,21 @@ def call_subprocess(
         proc.returncode and proc.returncode not in extra_ok_returncodes
     )
     if proc_had_error:
-        if on_returncode == 'raise':
-            if not showing_subprocess and log_failed_cmd:
-                # Then the subprocess streams haven't been logged to the
-                # console yet.
-                msg = make_subprocess_output_error(
-                    cmd_args=cmd,
-                    cwd=cwd,
-                    lines=all_output,
-                    exit_status=proc.returncode,
-                )
-                subprocess_logger.error(msg)
-            exc_msg = (
-                'Command errored out with exit status {}: {} '
-                'Check the logs for full command output.'
-            ).format(proc.returncode, command_desc)
-            raise SubProcessError(exc_msg)
-        elif on_returncode == 'warn':
-            subprocess_logger.warning(
-                'Command "{}" had error code {} in {}'.format(
-                    command_desc, proc.returncode, cwd)
+        if not showing_subprocess and log_failed_cmd:
+            # Then the subprocess streams haven't been logged to the
+            # console yet.
+            msg = make_subprocess_output_error(
+                cmd_args=cmd,
+                cwd=cwd,
+                lines=all_output,
+                exit_status=proc.returncode,
             )
-        elif on_returncode == 'ignore':
-            pass
-        else:
-            raise ValueError('Invalid value: on_returncode={!r}'.format(
-                             on_returncode))
+            subprocess_logger.error(msg)
+        exc_msg = (
+            'Command errored out with exit status {}: {} '
+            'Check the logs for full command output.'
+        ).format(proc.returncode, command_desc)
+        raise SubProcessError(exc_msg)
     return ''.join(all_output)
 
 
@@ -768,7 +756,6 @@ class VersionControl(object):
         cls,
         cmd,  # type: Union[List[str], CommandArgs]
         cwd=None,  # type: Optional[str]
-        on_returncode='raise',  # type: str
         extra_environ=None,  # type: Optional[Mapping[str, Any]]
         extra_ok_returncodes=None,  # type: Optional[Iterable[int]]
         log_failed_cmd=True  # type: bool
@@ -782,7 +769,6 @@ class VersionControl(object):
         cmd = make_command(cls.name, *cmd)
         try:
             return call_subprocess(cmd, cwd,
-                                   on_returncode=on_returncode,
                                    extra_environ=extra_environ,
                                    extra_ok_returncodes=extra_ok_returncodes,
                                    log_failed_cmd=log_failed_cmd)

From e9f738a3daec91b131ae985e16809d47b1cfdaff Mon Sep 17 00:00:00 2001
From: Devesh Kumar Singh <deveshkusingh@gmail.com>
Date: Fri, 15 May 2020 09:38:53 +0530
Subject: [PATCH 5/6] Bubble up SubProcessError to basecommand._main

---
 src/pip/_internal/cli/base_command.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/pip/_internal/cli/base_command.py b/src/pip/_internal/cli/base_command.py
index 535a49162..c52ffa2f2 100644
--- a/src/pip/_internal/cli/base_command.py
+++ b/src/pip/_internal/cli/base_command.py
@@ -28,6 +28,7 @@ from pip._internal.exceptions import (
     CommandError,
     InstallationError,
     PreviousBuildDirError,
+    SubProcessError,
     UninstallationError,
 )
 from pip._internal.utils.deprecation import deprecated
@@ -201,7 +202,8 @@ class Command(CommandContextMixIn):
             logger.debug('Exception information:', exc_info=True)
 
             return PREVIOUS_BUILD_DIR_ERROR
-        except (InstallationError, UninstallationError, BadCommand) as exc:
+        except (InstallationError, UninstallationError, BadCommand,
+                SubProcessError) as exc:
             logger.critical(str(exc))
             logger.debug('Exception information:', exc_info=True)
 

From 5c615aa775e343dfe7b97bdfc5cb826fa5691061 Mon Sep 17 00:00:00 2001
From: Devesh Kumar Singh <deveshkusingh@gmail.com>
Date: Fri, 15 May 2020 12:07:03 +0530
Subject: [PATCH 6/6] Update news entry

---
 news/7968.bugfix | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/news/7968.bugfix b/news/7968.bugfix
index d6959730a..36b282fc8 100644
--- a/news/7968.bugfix
+++ b/news/7968.bugfix
@@ -1 +1 @@
-Look for version string in the entire output of svn --version, not just the first line
+The VCS commands run by pip as subprocesses don't merge stdout and stderr anymore, improving the output parsing by subsequent commands.