Adds Python package management to depot_tools.

PRESUBMIT.py

-# Copyright (c) 2011 The Chromium Authors. All rights reserved.
+# Copyright (c) 2012 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.
 
 """Top-level presubmit script for depot tools.
 
 See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts for
 details on the presubmit API built into depot_tools.
 """
 
 
 def CommonChecks(input_api, output_api, tests_to_black_list):
   results = []
   import sys
   if not sys.version.startswith('2.5'):
     # Depot_tools has the particularity that it needs to be tested on python
     # 2.5. But we don't want the presubmit check to fail if it is not installed.
     results.append(output_api.PresubmitNotifyResult(
         'You should install python 2.5 and run ln -s $(which python2.5) python.'
         '\n'
         'A great place to put this symlink is in depot_tools.\n'
         'Otherwise, you break depot_tools on python 2.5, you get to keep the '
         'pieces.'))
 
 
   results.extend(input_api.canned_checks.CheckOwners(input_api, output_api))
   black_list = list(input_api.DEFAULT_BLACK_LIST) + [
       r'^cpplint\.py$',
       r'^cpplint_chromium\.py$',
       r'^python_bin[\/\\].+',
+      r'^site-packages-py[0-9]\.[0-9][\/\\].+',
       r'^svn_bin[\/\\].+',
       r'^testing_support[\/\\]_rietveld[\/\\].+']
   results.extend(input_api.canned_checks.RunPylint(
       input_api,
       output_api,
       white_list=[r'.*\.py$'],
       black_list=black_list))
 
   # TODO(maruel): Make sure at least one file is modified first.
   # TODO(maruel): If only tests are modified, only run them.
@@ skipping 66 matching lines @@
 
 
 def CheckChangeOnCommit(input_api, output_api):
   output = []
   output.extend(CommonChecks(input_api, output_api, []))
   output.extend(input_api.canned_checks.CheckDoNotSubmit(
       input_api,
       output_api))
   output.extend(RunGitClTests(input_api, output_api))
   return output