Removed dependency on pytz

testing_support/git/repo.py

Index: testing_support/git/repo.py
diff --git a/testing_support/git/repo.py b/testing_support/git/repo.py
index af45bafa3032df3e7946a13069b4952f1ff3be34..29cc70fc609341895933c4e3ea0bd261541d91bf 100644
--- a/testing_support/git/repo.py
+++ b/testing_support/git/repo.py
@@ -6,7 +6,6 @@ import atexit
 import collections
 import datetime
 import os
-import pytz
 import shutil
 import subprocess
 import sys
@@ -68,9 +67,12 @@ class GitRepo(object):
     Args:
       schema - An instance of GitRepoSchema
     """
+    class UTC(datetime.tzinfo):
+      def utcoffset(self, dt): return datetime.timedelta(0)
+
     self.repo_path = tempfile.mkdtemp(dir=self.BASE_TEMP_DIR)
     self.commit_map = {}
-    self._date = datetime.datetime(1970, 1, 1, tzinfo=pytz.utc)
+    self._date = datetime.datetime(1970, 1, 1, tzinfo=UTC())
 
     self.to_schema_refs = ['--branches']