Add git-map and git-short-map to depot_tools.

testing_support/git_test_utils.py

Index: testing_support/git_test_utils.py
diff --git a/testing_support/git_test_utils.py b/testing_support/git_test_utils.py
index bf583c684db142a6b3ced9b9c1b4b3b049f15cac..5becad94ba58e0ece7bbcbdaa812fee034d1d0d9 100644
--- a/testing_support/git_test_utils.py
+++ b/testing_support/git_test_utils.py
@@ -256,6 +256,7 @@ class GitRepo(object):
     self.git('init')
     for commit in schema.walk():
       self._add_schema_commit(commit, schema.data_for(commit.name))
+      self.last_commit = self[commit.name]
     if schema.master:
       self.git('update-ref', 'master', self[schema.master])
 
@@ -321,7 +322,7 @@ class GitRepo(object):
     self.commit_map[commit.name] = self.git('rev-parse', 'HEAD').stdout.strip()
     self.git('tag', 'tag_%s' % commit.name, self[commit.name])
     if commit.is_branch:
-      self.git('update-ref', 'branch_%s' % commit.name, self[commit.name])
+      self.git('branch', '-f', 'branch_%s' % commit.name, self[commit.name])
 
   def git(self, *args, **kwargs):
     """Runs a git command specified by |args| in this repo."""
@@ -394,6 +395,9 @@ class GitRepoReadOnlyTestBase(GitRepoSchemaTestBase):
     assert cls.REPO is not None
     cls.repo = cls.r_schema.reify()
 
+  def setUp(self):
+    self.repo.git('checkout', '-f', self.repo.last_commit)
+
   @classmethod
   def tearDownClass(cls):
     cls.repo.nuke()