Fix argument checking in gcl.py

gcl.py

 #!/usr/bin/python
 # Copyright (c) 2006-2009 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 649 matching lines @@
     return function(change_info)
   defer_attributes(function, hook)
   hook.need_change = True
   hook.no_args = True
   return hook
 
 
 def need_change_and_args(function):
   """Converts args -> change_info."""
   def hook(args):
+    if not args:
+      ErrorExit("You need to pass a change list name")
     change_info = ChangeInfo.Load(args.pop(0), GetRepositoryRoot(), True, True)
     return function(change_info, args)
   defer_attributes(function, hook)
   hook.need_change = True
   return hook
 
 
 def no_args(function):
   """Make sure no args are passed."""
   def hook(args):
@@ skipping 628 matching lines @@
     argv = ['help']
   command = Command(argv[0])
   if command:
     return command(argv[1:])
   # Unknown command, try to pass that to svn
   return CMDpassthru(argv)
 
 
 if __name__ == "__main__":
   sys.exit(main(sys.argv[1:]))