Style cleanup in auxiliary bisect-related scripts.

tools/prepare-bisect-perf-regression.py

 #!/usr/bin/env python
 # Copyright (c) 2013 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.
 
 """Prepare Performance Test Bisect Tool
 
 This script is used by a trybot to create a working directory and sync an
 initial copy of the depot for use in bisecting performance regressions.
 
 An example usage:
 
 ./tools/prepare-bisect-perf-regressions.py --working_directory "~/builds"
   --output_buildbot_annotations
 
 Would result in creating ~/builds/bisect and then populating it with a copy of
 the depot.
-
 """
 
 import optparse
 import sys
 
 from auto_bisect import bisect_utils
 
 
 def main():
+  """Does an initial checkout of Chromium then exits."""
 
   usage = ('%prog [options] [-- chromium-options]\n'
            'Prepares a temporary depot for use on a trybot.')
 
   parser = optparse.OptionParser(usage=usage)
 
   parser.add_option('-w', '--working_directory',
                     type='str',
                     help='Path to the working directory where the script will '
                     'do an initial checkout of the chromium depot. The '
                     'files will be placed in a subdirectory "bisect" under '
                     'working_directory and that will be used to perform the '
                     'bisection.')
   parser.add_option('--output_buildbot_annotations',
-                    action="store_true",
+                    action='store_true',
                     help='Add extra annotation output for buildbot.')
   parser.add_option('--target_platform',
                     type='choice',
                     choices=['chromium', 'cros', 'android'],
                     default='chromium',
                     help='The target platform. Choices are "chromium" (current '
                     'platform), "cros", or "android". If you specify something '
                     'other than "chromium", you must be properly set up to '
                     'build that platform.')
-  (opts, args) = parser.parse_args()
+  opts, _ = parser.parse_args()
 
   if not opts.working_directory:
     print 'Error: missing required parameter: --working_directory'
     print
     parser.print_help()
     return 1
 
   if not bisect_utils.CheckIfBisectDepotExists(opts):
     try:
-      bisect_utils.CreateBisectDirectoryAndSetupDepot(opts,
-          bisect_utils.DEFAULT_GCLIENT_CUSTOM_DEPS)
+      bisect_utils.CreateBisectDirectoryAndSetupDepot(
+          opts, bisect_utils.DEFAULT_GCLIENT_CUSTOM_DEPS)
     except RuntimeError:
       return 1
   return 0
 
 
 if __name__ == '__main__':
   sys.exit(main())