Add a virtualenv-based python bootstrapping service to infra.

infra/tools/buildbot/__main__.py

 #!/usr/bin/env python
 # 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.
 
 import argparse
 import sys
 import time
 
-from infra.ext import requests
+import requests
 
 
 def get_builders(json_base):
   return requests.get(
       'https://%s/json/builders?filter=False' % json_base).json().keys()
 
 
 def get_builder(json_base, builder):
   return requests.get(
       'https://%s/json/builders/%s?filter=False' % (json_base, builder)).json()
@@ skipping 60 matching lines @@
   cmd_parser_current.add_argument('--blame', action='store_true')
 
   args = parser.parse_args(argv)
 
   # Dispatch to the function set for target subparser using set_defaults.
   return args.func(args)
 
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv[1:]))