Pass shallow flag through gclient to git_cache.py

gclient.py

 #!/usr/bin/env python
 # 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.
 
 """Meta checkout manager supporting both Subversion and GIT."""
 # Files
 #   .gclient      : Current client configuration, written by 'config' command.
 #                   Format is a Python script defining 'solutions', a list whose
 #                   entries each are maps binding the strings "name" and "url"
@@ skipping 1720 matching lines @@
                          'platform(s); \'all\' will process all deps_os '
                          'references')
   parser.add_option('-m', '--manually_grab_svn_rev', action='store_true',
                     help='Skip svn up whenever possible by requesting '
                          'actual HEAD revision from the repository')
   parser.add_option('--upstream', action='store_true',
                     help='Make repo state match upstream branch.')
   parser.add_option('--output-json',
                     help='Output a json document to this path containing '
                          'summary information about the sync.')
+  parser.add_option('--shallow', action='store_true',
+                    help='GIT ONLY - Do a shallow clone into the cache dir. '
+                         'Requires Git 1.9+')
   (options, args) = parser.parse_args(args)
   client = GClient.LoadCurrentConfig(options)
 
   if not client:
     raise gclient_utils.Error('client not configured; see \'gclient config\'')
 
   if options.revisions and options.head:
     # TODO(maruel): Make it a parser.error if it doesn't break any builder.
     print('Warning: you cannot use both --head and --revision')
 
@@ skipping 231 matching lines @@
     print >> sys.stderr, 'Error: %s' % str(e)
     return 1
   finally:
     gclient_utils.PrintWarnings()
 
 
 if '__main__' == __name__:
   sys.exit(Main(sys.argv[1:]))
 
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