Fix broken "gcl diff cl" command. We need to use full paths, not...

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 1148 matching lines @@
 
 @attrs(usage='<svn options>')
 def CMDdiff(args):
   """Diffs all files in the changelist or all files that aren't in a CL."""
   files = None
   if args:
     change_info = ChangeInfo.Load(args.pop(0), GetRepositoryRoot(), True, True)
     files = change_info.GetFileNames()
   else:
     files = GetFilesNotInCL()
-  return RunShellWithReturnCode(['svn', 'diff'] + files + args,
-                                print_output=True)[1]
+
+  root = GetRepositoryRoot()
+  cmd = ['svn', 'diff']
+  cmd.extend([os.path.join(root, x) for x in files])
+  cmd.extend(args)
+  return RunShellWithReturnCode(cmd, print_output=True)[1]
 
 
 @no_args
 def CMDsettings():
   """Prints code review settings for this checkout."""
   # Force load settings
   GetCodeReviewSetting("UNKNOWN");
   del CODEREVIEW_SETTINGS['__just_initialized']
   print '\n'.join(("%s: %s" % (str(k), str(v))
                     for (k,v) in CODEREVIEW_SETTINGS.iteritems()))
@@ skipping 132 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:]))