Fix: Use -C instead of --git-dir.

unittests/package_test.py

 #!/usr/bin/env python
 # Copyright 2015 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import doctest
 import os
 import subprocess
 import sys
 import unittest
@@ skipping 49 matching lines @@
     self.mock_os.path.exists.return_value = False
     self.mock_os.path.isdir.return_value = False
 
     self.repo_spec.checkout(self.context)
 
     self.mock_subprocess.check_output.assert_any_call(
         ['git', 'clone', self.REPO_URL,
          os.path.join(self.context.package_dir, 'funny_recipes')])
     self.mock_subprocess.check_output.assert_any_call(
         ['git',
-         '--git-dir', 'repo/root/recipes/.recipe_deps/funny_recipes/.git',
+         '-C', 'repo/root/recipes/.recipe_deps/funny_recipes',
          'reset', '-q', '--hard', 'deadbeef'])
 
 
 class MockProtoFile(package.ProtoFile):
   def __init__(self, path, text):
     super(MockProtoFile, self).__init__(path)
     self._text = text
 
   @property
   def path(self):
@@ skipping 131 matching lines @@
     self.assertEqual(foo_deps.repo_spec.path, '/path/to/local/foo')
 
 
 def load_tests(_loader, tests, _ignore):
   tests.addTests(doctest.DocTestSuite(package))
   return tests
 
 
 if __name__ == '__main__':
   result = unittest.main()