allow running "git cl format" from subdirectories

git_cl.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.
 
 # Copyright (C) 2008 Evan Martin <martine@danga.com>
 
 """A git-command for integrating reviews on Rietveld."""
 
 import difflib
@@ skipping 2103 matching lines @@
     DieWithError('Could not find base commit for this branch. '
                  'Are you in detached state?')
 
   diff_cmd.append(upstream_commit)
 
   # Handle source file filtering.
   diff_cmd.append('--')
   diff_cmd += ['*' + ext for ext in CLANG_EXTS]
   diff_output = RunGit(diff_cmd)
 
+  top_dir = RunGit(["rev-parse", "--show-toplevel"]).rstrip('\n')
+
   if opts.full:
     # diff_output is a list of files to send to clang-format.
     files = diff_output.splitlines()
     if not files:
       print "Nothing to format."
       return 0
-    RunCommand(['clang-format', '-i', '-style', 'Chromium'] + files)
+    RunCommand(['clang-format', '-i', '-style', 'Chromium'] + files,
+               cwd=top_dir)
   else:
     # diff_output is a patch to send to clang-format-diff.py
     cfd_path = os.path.join('/usr', 'lib', 'clang-format',
                             'clang-format-diff.py')
     if not os.path.exists(cfd_path):
       DieWithError('Could not find clang-format-diff at %s.' % cfd_path)
     cmd = [sys.executable, cfd_path, '-style', 'Chromium']
-    RunCommand(cmd, stdin=diff_output)
+    RunCommand(cmd, stdin=diff_output, cwd=top_dir)
 
   return 0
 
 
 ### Glue code for subcommand handling.
 
 
 def Commands():
   """Returns a dict of command and their handling function."""
   module = sys.modules[__name__]
@@ skipping 122 matching lines @@
   GenUsage(parser, 'help')
   return CMDhelp(parser, argv)
 
 
 if __name__ == '__main__':
   # These affect sys.stdout so do it outside of main() to simplify mocks in
   # unit testing.
   fix_encoding.fix_encoding()
   colorama.init()
   sys.exit(main(sys.argv[1:]))