repo: raise min version of git

The git-2.10 series was released in 2016.  Since we're moving to
require Python 3.6 which was also released in 2016, bumping up the
git version seems reasonable.  Also we don't really test any git
versions close to as old as 1.7.2 which was released in 2010.

Change-Id: Ib71b714de6cd0b7dd50d0b300b108a560ee27331
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/253134
Tested-by: Mike Frysinger <vapier@google.com>
Reviewed-by: David Pursehouse <dpursehouse@collab.net>

git_command.py

@@ -28,7 +28,8 @@ from repo_trace import REPO_TRACE, IsTrace, Trace
 from wrapper import Wrapper
 
 GIT = 'git'
-MIN_GIT_VERSION = (1, 5, 4)
+# Should keep in sync with the "repo" launcher file.
+MIN_GIT_VERSION = (2, 10, 2)
 GIT_DIR = 'GIT_DIR'
 
 LAST_GITDIR = None

repo

@@ -86,7 +86,7 @@ TACbBS+Up3RpfYVfd63c1cDdlru13pQAn3NQy/SN858MkxN+zym86UBgOad2
 """
 
 GIT = 'git'                      # our git command
-MIN_GIT_VERSION = (1, 7, 2)      # minimum supported git version
+MIN_GIT_VERSION = (2, 10, 2)     # minimum supported git version
 repodir = '.repo'                # name of repo's private directory
 S_repo = 'repo'                  # special repo repository
 S_manifests = 'manifests'        # special manifest repository

tests/test_git_command.py

@@ -35,7 +35,7 @@ class GitCallUnitTest(unittest.TestCase):
     # We don't dive too deep into the values here to avoid having to update
     # whenever git versions change.  We do check relative to this min version
     # as this is what `repo` itself requires via MIN_GIT_VERSION.
-    MIN_GIT_VERSION = (1, 7, 2)
+    MIN_GIT_VERSION = (2, 10, 2)
     self.assertTrue(isinstance(ver.major, int))
     self.assertTrue(isinstance(ver.minor, int))
     self.assertTrue(isinstance(ver.micro, int))