Try to get clang upload script working on Windows.

tools/clang/scripts/upload_revision.py

 #!/usr/bin/env python
 # Copyright (c) 2016 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 script takes a Clang revision as an argument, it then
 creates a feature branch, puts this revision into update.py, uploads
 a CL, triggers Clang Upload try bots, and tells what to do next"""
 
 import argparse
 import fnmatch
 import itertools
 import os
 import re
 import shutil
 import subprocess
 import sys
 
 # Path constants.
 THIS_DIR = os.path.dirname(__file__)
 UPDATE_PY_PATH = os.path.join(THIS_DIR, "update.py")
 CHROMIUM_DIR = os.path.abspath(os.path.join(THIS_DIR, '..', '..', '..'))
 
+is_win = sys.platform.startswith('win32')
 
 def PatchRevision(clang_revision, clang_sub_revision):
-  with open(UPDATE_PY_PATH, 'r') as f:
+  with open(UPDATE_PY_PATH, 'rb') as f:
     content = f.read()
   m = re.search("CLANG_REVISION = '([0-9]+)'", content)
   clang_old_revision = m.group(1)
   content = re.sub("CLANG_REVISION = '[0-9]+'",
                    "CLANG_REVISION = '{}'".format(clang_revision),
                    content, count=1)
   content = re.sub("CLANG_SUB_REVISION=[0-9]+",
                    "CLANG_SUB_REVISION={}".format(clang_sub_revision),
                    content, count=1)
-  with open(UPDATE_PY_PATH, 'w') as f:
+  with open(UPDATE_PY_PATH, 'wb') as f:
     f.write(content)
   return clang_old_revision
 
 
 def Git(args):
-  subprocess.check_call(["git"] + args)
+  # Needs shell=True on Windows due to git.bat in depot_tools.
+  subprocess.check_call(["git"] + args, shell=is_win)
 
 def main():
   parser = argparse.ArgumentParser(description='upload new clang revision')
   parser.add_argument('clang_revision', metavar='CLANG_REVISION',
                       type=int, nargs=1,
                       help='Clang revision to build the toolchain for.')
   parser.add_argument('clang_sub_revision', metavar='CLANG_SUB_REVISION',
                       type=int, nargs='?', default=1,
                       help='Clang sub-revision to build the toolchain for.')
 
   args = parser.parse_args()
 
   clang_revision = args.clang_revision[0]
   clang_sub_revision = args.clang_sub_revision
+  # Needs shell=True on Windows due to git.bat in depot_tools.
   git_revision = subprocess.check_output(
-      ["git", "rev-parse", "origin/master"]).strip()
+      ["git", "rev-parse", "origin/master"], shell=is_win).strip()
   print "Making a patch for Clang revision r{}-{}".format(
       clang_revision, clang_sub_revision)
   print "Chrome revision: {}".format(git_revision)
   clang_old_revision = PatchRevision(clang_revision, clang_sub_revision)
 
   Git(["checkout", "-b", "clang-{}-{}".format(
       clang_revision, clang_sub_revision)])
   Git(["add", UPDATE_PY_PATH])
 
   commit_message = 'Ran `{}`.'.format(' '.join(sys.argv))
   Git(["commit", "-m", "Roll clang {}:{}.\n\n{}".format(
       clang_old_revision, clang_revision, commit_message)])
 
   Git(["cl", "upload"])
   Git(["cl", "try", "-b", "linux_upload_clang", "-r", git_revision])
   Git(["cl", "try", "-b", "mac_upload_clang", "-r", git_revision])
   Git(["cl", "try", "-b", "win_upload_clang", "-r", git_revision])
 
   print ("Please, wait until the try bots succeeded "
          "and then push the binaries to goma.")
 
 if __name__ == '__main__':
   sys.exit(main())