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

git_number.py

 #!/usr/bin/env python
 # Copyright 2013 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.
 
 """Usage: %prog [options] [<commitref>]*
 
 If no <commitref>'s are supplied, it defaults to HEAD.
 
 Calculates the generation number for one or more commits in a git repo.
@@ skipping 135 matching lines @@
     with git.ScopedPool(kind=POOL_KIND) as leaf_pool:
       for item in leaf_pool.imap(leaf_map_fn, prefixes_trees):
         updater.stdin.write(item)
         inc()
 
     updater.stdin.close()
     updater.wait()
     assert updater.returncode == 0
 
     tree_id = git.run('write-tree', env=env)
-    commit_cmd = ['commit-tree', '-m', msg, '-p'] + git.hashes(REF)
+    commit_cmd = ['commit-tree', '-m', msg, '-p'] + git.hash_multi(REF)
     for t in targets:
       commit_cmd.extend(['-p', binascii.hexlify(t)])
     commit_cmd.append(tree_id)
     commit_hash = git.run(*commit_cmd)
     git.run('update-ref', REF, commit_hash)
   DIRTY_TREES.clear()
 
 
 def preload_tree(prefix):
   """Returns the prefix and parsed tree object for the specified prefix."""
@@ skipping 91 matching lines @@
       finalize(targets)
 
     print '\n'.join(map(str, map(get_num, targets)))
     return 0
   except KeyboardInterrupt:
     return 1
 
 
 if __name__ == '__main__':  # pragma: no cover
   sys.exit(main())