Git Cache speculative fix for windows

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."""
 
 from __future__ import print_function
 import errno
 import logging
@@ skipping 388 matching lines @@
       self._fetch(rundir, verbose, depth)
     except RefsHeadsFailedToFetch:
       # This is a major failure, we need to clean and force a bootstrap.
       gclient_utils.rmtree(rundir)
       self.print(GIT_CACHE_CORRUPT_MESSAGE)
       tempdir = self._ensure_bootstrapped(depth, bootstrap, force=True)
       assert tempdir
       self._fetch(tempdir or self.mirror_path, verbose, depth)
     finally:
       if tempdir:
-        os.rename(tempdir, self.mirror_path)
+        try:
+          os.rename(tempdir, self.mirror_path)
+        except OSError as e:
+          # This is somehow racy on Windows.
+          # Catching OSError because WindowsError isn't portable and
+          # pylint complains.
+          self.print('Error moving %s to %s: %s' % (tempdir, self.mirror_path,
+                                                    str(e)))
       if not ignore_lock:
         lockfile.unlock()
 
   def update_bootstrap(self, prune=False):
     # The files are named <git number>.zip
     gen_number = subprocess.check_output(
         [self.git_exe, 'number', 'master'], cwd=self.mirror_path).strip()
     self.RunGit(['gc'])  # Run Garbage Collect to compress packfile.
     # Creating a temp file and then deleting it ensures we can use this name.
     _, tmp_zipfile = tempfile.mkstemp(suffix='.zip')
@@ skipping 204 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:]))