Add more python 2.5 compatibility.

subprocess2.py

 # coding=utf8
 # 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.
 """Collection of subprocess wrapper functions.
 
 In theory you shouldn't need anything else in subprocess, or this module failed.
 """
 
+from __future__ import with_statement
 import logging
 import os
 import subprocess
 import sys
 import tempfile
 import time
 import threading
 
 # Constants forwarded from subprocess.
 PIPE = subprocess.PIPE
@@ skipping 173 matching lines @@
 
   Discards communicate()[1]. By default sets stderr=STDOUT.
 
   Throws if return code is not 0.
 
   Works even prior to python 2.7.
   """
   if kwargs.get('stderr') is None:
     kwargs['stderr'] = STDOUT
   return check_call(args, stdout=PIPE, **kwargs)[0]