Suppress spurious warning about overriding cache dir.

git_cache.py

 #!/usr/bin/env python
 # Copyright 2014 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.
 
 """A git command for managing a local cache of git repositories."""
 
 import errno
 import logging
 import optparse
@@ skipping 272 matching lines @@
     self.add_option('-v', '--verbose', action='count', default=0,
                     help='Increase verbosity (can be passed multiple times)')
 
   def parse_args(self, args=None, values=None):
     options, args = optparse.OptionParser.parse_args(self, args, values)
 
     try:
       global_cache_dir = subprocess.check_output(
           [GIT_EXECUTABLE, 'config', '--global', 'cache.cachepath']).strip()
       if options.cache_dir:
-        logging.warn('Overriding globally-configured cache directory.')
+        if global_cache_dir and (
+            os.path.abspath(options.cache_dir) !=
+            os.path.abspath(global_cache_dir)):
+          logging.warn('Overriding globally-configured cache directory.')
       else:
         options.cache_dir = global_cache_dir
     except subprocess.CalledProcessError:
       if not options.cache_dir:
         self.error('No cache directory specified on command line '
                    'or in cache.cachepath.')
     options.cache_dir = os.path.abspath(options.cache_dir)
 
     levels = [logging.WARNING, logging.INFO, logging.DEBUG]
     logging.basicConfig(level=levels[min(options.verbose, len(levels) - 1)])
 
     return options, args
 
 
 def main(argv):
   dispatcher = subcommand.CommandDispatcher(__name__)
   return dispatcher.execute(OptionParser(), argv)
 
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv[1:]))