Auto-roll script: Add dirty tree check and git pull

tools/autoroller/roll_chromium_revision.py

 #!/usr/bin/env python
 # Copyright (c) 2015 The WebRTC project authors. All Rights Reserved.
 #
 # Use of this source code is governed by a BSD-style license
 # that can be found in the LICENSE file in the root of the source
 # tree. An additional intellectual property rights grant can be found
 # in the file PATENTS.  All contributing project authors may
 # be found in the AUTHORS file in the root of the source tree.
 
 """Script to roll chromium_revision in the WebRTC DEPS file."""
@@ skipping 271 matching lines @@
 
 
 def UpdateDeps(deps_filename, old_cr_revision, new_cr_revision):
   """Update the DEPS file with the new revision."""
   with open(deps_filename, 'rb') as deps_file:
     deps_content = deps_file.read()
   deps_content = deps_content.replace(old_cr_revision, new_cr_revision)
   with open(deps_filename, 'wb') as deps_file:
     deps_file.write(deps_content)
 
+def _IsTreeClean():
+  stdout, _ = _RunCommand(['git', 'status', '--porcelain'])
+  if len(stdout) == 0:
+    return True
+
+  logging.error('Dirty/unversioned files:\n%s', stdout)
+  return False
 
 def _CreateRollBranch(dry_run):
   current_branch = _RunCommand(
       ['git', 'rev-parse', '--abbrev-ref', 'HEAD'])[0].splitlines()[0]
   if current_branch != 'master':
     logging.error('Please checkout the master branch and re-run this script.')
     if not dry_run:
       sys.exit(-1)
 
+  logging.info('Updating master branch...')
+  if not dry_run:
+    _RunCommand(['git', 'pull'])
   logging.info('Creating roll branch: %s', ROLL_BRANCH_NAME)
   if not dry_run:
     _RunCommand(['git', 'checkout', '-b', ROLL_BRANCH_NAME])
 
 
 def _RemovePreviousRollBranch(dry_run):
   active_branch, branches = _GetBranches()
   if active_branch == ROLL_BRANCH_NAME:
     active_branch = 'master'
   if ROLL_BRANCH_NAME in branches:
@@ skipping 35 matching lines @@
                        'tryjobs.'))
   p.add_argument('-v', '--verbose', action='store_true', default=False,
                  help='Be extra verbose in printing of log messages.')
   opts = p.parse_args()
 
   if opts.verbose:
     logging.basicConfig(level=logging.DEBUG)
   else:
     logging.basicConfig(level=logging.INFO)
 
+  if not _IsTreeClean():
+    logging.error('Please clean your local checkout first.')
+    return 1
+
   if opts.clean:
     _RemovePreviousRollBranch(opts.dry_run)
 
   if not opts.revision:
     lkgr_contents = ReadUrlContent(CHROMIUM_LKGR_URL)
     logging.info('No revision specified. Using LKGR: %s', lkgr_contents[0])
     opts.revision = lkgr_contents[0]
 
   deps_filename = os.path.join(CHECKOUT_ROOT_DIR, 'DEPS')
   local_deps = ParseLocalDepsFile(deps_filename)
@@ skipping 16 matching lines @@
   _CreateRollBranch(opts.dry_run)
   UpdateDeps(deps_filename, current_cr_rev, opts.revision)
   _LocalCommit(commit_msg, opts.dry_run)
   _UploadCL(opts.dry_run)
   _LaunchTrybots(opts.dry_run)
   return 0
 
 
 if __name__ == '__main__':
   sys.exit(main())