Refactor the way that git executables are launched in depot tools.

git-try

-#!/bin/sh
+#!/bin/bash
 # Copyright (c) 2011 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.
 
-# Test if this script is running under a MSys install.  If it is, we will
-# hardcode the path to Python where possible.
-OUTPUT="$(uname | grep 'MINGW')"
-MINGW=$?
+# git_try.py - Commits a patch to the SVN try patch repo.
+#              It is highly recommended to use `git cl try` instead.
 
-if [ $MINGW = 0 ]; then
-  base_dir="${0%\\*}"
-else
-  base_dir=$(dirname "$0")
-fi
-
-if [ -e "$base_dir/python.bat" -a $MINGW = 0 ]; then
-  PYTHONDONTWRITEBYTECODE=1 cmd.exe //c "$base_dir\\python.bat" "$base_dir\\git_try.py" "$@"
-else
-  PYTHONDONTWRITEBYTECODE=1 exec "$base_dir/git_try.py" "$@"
-fi
+. ${0/%$(basename "$0")/python_git_runner.sh}