git cl assumes no shell is used.

git_cl.py

 #!/usr/bin/env python
 # Copyright (c) 2011 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 logging
@@ skipping 37 matching lines @@
 DESCRIPTION_BACKUP_FILE = '~/.git_cl_description_backup'
 
 
 def DieWithError(message):
   print >> sys.stderr, message
   sys.exit(1)
 
 
 def RunCommand(args, error_ok=False, error_message=None, **kwargs):
   try:
-    return subprocess2.check_output(args, **kwargs)
+    return subprocess2.check_output(args, shell=False, **kwargs)
   except subprocess2.CalledProcessError, e:
     if not error_ok:
       DieWithError(
           'Command "%s" failed.\n%s' % (
             ' '.join(args), error_message or e.stdout or ''))
     return e.stdout
 
 
 def RunGit(args, **kwargs):
   """Returns stdout."""
@@ skipping 1361 matching lines @@
              'and retry or visit go/isgaeup.\n%s') % (e.code, str(e)))
 
   # Not a known command. Default to help.
   GenUsage(parser, 'help')
   return CMDhelp(parser, argv)
 
 
 if __name__ == '__main__':
   fix_encoding.fix_encoding()
   sys.exit(main(sys.argv[1:]))