Re-implement Git version parsing with regex

news/10117.removal.rst

@@ -0,0 +1,2 @@
+Git version parsing is now done with regular expression to prepare for the
+pending upstream removal of non-PEP-440 version parsing logic.

src/pip/_internal/vcs/git.py

@@ -6,9 +6,6 @@
 import urllib.request
 from typing import List, Optional, Tuple
 
-from pip._vendor.packaging.version import _BaseVersion
-from pip._vendor.packaging.version import parse as parse_version
-
 from pip._internal.exceptions import BadCommand, InstallationError
 from pip._internal.utils.misc import HiddenText, display_path, hide_url
 from pip._internal.utils.subprocess import make_command
@@ -29,6 +26,14 @@
 logger = logging.getLogger(__name__)
 
 
+GIT_VERSION_REGEX = re.compile(
+    r"^git version "  # Prefix.
+    r"(\d+)"  # Major.
+    r"\.(\d+)"  # Dot, minor.
+    r"(?:\.(\d+))?"  # Optional dot, patch.
+    r".*$"  # Suffix, including any pre- and post-release segments we don't care about.
+)
+
 HASH_REGEX = re.compile('^[a-fA-F0-9]{40}$')
 
 # SCP (Secure copy protocol) shorthand. e.g. 'git@example.com:foo/bar.git'
@@ -83,21 +88,14 @@ def is_immutable_rev_checkout(self, url, dest):
         )
         return not is_tag_or_branch
 
-    def get_git_version(self):
-        # type: () -> _BaseVersion
-        VERSION_PFX = 'git version '
+    def get_git_version(self) -> Tuple[int, ...]:
         version = self.run_command(
             ['version'], show_stdout=False, stdout_only=True
         )
-        if version.startswith(VERSION_PFX):
-            version = version[len(VERSION_PFX):].split()[0]
-        else:
-            version = ''
-        # get first 3 positions of the git version because
-        # on windows it is x.y.z.windows.t, and this parses as
-        # LegacyVersion which always smaller than a Version.
-        version = '.'.join(version.split('.')[:3])
-        return parse_version(version)
+        match = GIT_VERSION_REGEX.match(version)
+        if not match:
+            return ()
+        return tuple(int(c) for c in match.groups())
 
     @classmethod
     def get_current_branch(cls, location):
@@ -301,7 +299,7 @@ def switch(self, dest, url, rev_options):
     def update(self, dest, url, rev_options):
         # type: (str, HiddenText, RevOptions) -> None
         # First fetch changes from the default remote
-        if self.get_git_version() >= parse_version('1.9.0'):
+        if self.get_git_version() >= (1, 9):
             # fetch tags in addition to everything else
             self.run_command(['fetch', '-q', '--tags'], cwd=dest)
         else:

tests/unit/test_vcs.py

@@ -4,7 +4,6 @@
 from unittest.mock import patch
 
 import pytest
-from pip._vendor.packaging.version import parse as parse_version
 
 from pip._internal.exceptions import BadCommand, InstallationError
 from pip._internal.utils.misc import hide_url, hide_value
@@ -483,7 +482,7 @@ def test_subversion__get_url_rev_options():
 
 def test_get_git_version():
     git_version = Git().get_git_version()
-    assert git_version >= parse_version('1.0.0')
+    assert git_version >= (1, 0, 0)
 
 
 @pytest.mark.parametrize('use_interactive,is_atty,expected', [