Use our own copy of strtobool, rather than the one from distutils

src/pip/_internal/cli/cmdoptions.py

@@ -13,7 +13,6 @@ pass on state. To be consistent, all options will follow this design.
 import os
 import textwrap
 import warnings
-from distutils.util import strtobool
 from functools import partial
 from optparse import SUPPRESS_HELP, Option, OptionGroup
 from textwrap import dedent
@@ -27,6 +26,7 @@ from pip._internal.models.format_control import FormatControl
 from pip._internal.models.index import PyPI
 from pip._internal.models.target_python import TargetPython
 from pip._internal.utils.hashes import STRONG_HASHES
+from pip._internal.utils.misc import strtobool
 from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
 if MYPY_CHECK_RUNNING:

src/pip/_internal/cli/parser.py

@@ -8,13 +8,12 @@ import optparse
 import shutil
 import sys
 import textwrap
-from distutils.util import strtobool
 
 from pip._vendor.contextlib2 import suppress
 
 from pip._internal.cli.status_codes import UNKNOWN_ERROR
 from pip._internal.configuration import Configuration, ConfigurationError
-from pip._internal.utils.misc import redact_auth_from_url
+from pip._internal.utils.misc import redact_auth_from_url, strtobool
 
 logger = logging.getLogger(__name__)
 

src/pip/_internal/utils/misc.py

@@ -244,6 +244,23 @@ def ask_password(message):
     return getpass.getpass(message)
 
 
+def strtobool(val):
+    # type: (str) -> int
+    """Convert a string representation of truth to true (1) or false (0).
+
+    True values are 'y', 'yes', 't', 'true', 'on', and '1'; false values
+    are 'n', 'no', 'f', 'false', 'off', and '0'.  Raises ValueError if
+    'val' is anything else.
+    """
+    val = val.lower()
+    if val in ('y', 'yes', 't', 'true', 'on', '1'):
+        return 1
+    elif val in ('n', 'no', 'f', 'false', 'off', '0'):
+        return 0
+    else:
+        raise ValueError("invalid truth value %r" % (val,))
+
+
 def format_size(bytes):
     # type: (float) -> str
     if bytes > 1000 * 1000: