Add some error checking to CMDpassthru for invalid arguments.

gcl.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.
 
 """\
 Wrapper script around Rietveld's upload.py that simplifies working with groups
 of files.
 """
 
@@ skipping 1321 matching lines @@
   os.rename(src_file, dst_file)
   print "Change '%s' renamed '%s'." % (src, dst)
   return 0
 
 
 def CMDpassthru(args):
   """Everything else that is passed into gcl we redirect to svn.
 
   It assumes a change list name is passed and is converted with the files names.
   """
+  if not args or len(args) < 2:
+    ErrorExit("You need to pass a change list name for this svn fall-through "
+              "command")
   cl_name = args[1]
   args = ["svn", args[0]]
   if len(args) > 1:
     root = GetRepositoryRoot()
     change_info = ChangeInfo.Load(cl_name, root, True, True)
     args.extend([os.path.join(root, x) for x in change_info.GetFileNames()])
   return RunShellWithReturnCode(args, print_output=True)[1]
 
 
 def Command(name):
@@ skipping 83 matching lines @@
       raise
     print >> sys.stderr, (
         'AppEngine is misbehaving and returned HTTP %d, again. Keep faith '
         'and retry or visit go/isgaeup.\n%s') % (e.code, str(e))
     return 1
 
 
 if __name__ == "__main__":
   fix_encoding.fix_encoding()
   sys.exit(main(sys.argv[1:]))