Add trivial git-bash so that it can always drop you into a bash term,

git-bash

Index: git-bash
diff --git a/git-bash b/git-bash
new file mode 100755
index 0000000000000000000000000000000000000000..0a5be93217497ea9885fb7a6adb54bd0b7e3714b
--- /dev/null
+++ b/git-bash
@@ -0,0 +1,11 @@
+#!/usr/bin/env bash
+# Copyright 2014 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.
+
+# This apparently useless file enables windows users to get access to
+# depot_tools' built-in bash.exe. When git executes this file as in `git bash`,
+# it has bash and related tools pre-installed in the environment. Therefore even
+# though 'bash' from cmd.exe doesn't work, bash here does work as you'd expect.
+
+bash "$@"