Rationalize the git config settings for index-pack performance.

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 163 matching lines @@
   filter_fn = lambda l: '[up to date]' not in l
   if options.verbose:
     v = ['-v', '--progress']
     filter_fn = None
 
   d = []
   if options.depth:
     d = ['--depth', '%d' % options.depth]
 
   def _config(directory):
-    RunGit(['config', 'core.deltaBaseCacheLimit', '2g'],
-           cwd=directory)
+    RunGit(['config', 'core.deltaBaseCacheLimit',
+            gclient_utils.DefaultDeltaBaseCacheLimit()], cwd=directory)
     RunGit(['config', 'remote.origin.url', url],
            cwd=directory)
     RunGit(['config', '--replace-all', 'remote.origin.fetch',
             '+refs/heads/*:refs/heads/*'],
            cwd=directory)
     RunGit(['config', '--add', 'remote.origin.fetch',
             '+refs/tags/*:refs/tags/*'],
            cwd=directory)
     for ref in options.ref or []:
       ref = ref.rstrip('/')
@@ skipping 109 matching lines @@
     return options, args
 
 
 def main(argv):
   dispatcher = subcommand.CommandDispatcher(__name__)
   return dispatcher.execute(OptionParser(), argv)
 
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv[1:]))