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

git-short-map

Index: git-short-map
diff --git a/git-new-tracking-branch b/git-short-map
similarity index 64%
copy from git-new-tracking-branch
copy to git-short-map
index 0fbe2efde90f0b902de1270dad443e0525fe5e1f..e98c42ef6d93cc4ee3a9ae93beb1d6ad1dc046f5 100755
--- a/git-new-tracking-branch
+++ b/git-short-map
@@ -3,5 +3,4 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-NEW_BRANCH=${1?Must supply new branch name as first argument}
-git checkout --track -b "$NEW_BRANCH"
+. ${0/%$(basename "$0")/python_git_runner.sh}