Fix a typo in gcl.py.

BUG=none
TEST=gcl change foo does not return Unknown command: 'change' after editing the CL.
Review URL: http://codereview.chromium.org/1997003

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@46602 0039d316-1c4b-4281-b951-d872f2087c98

gcl.py

@@ -1222,7 +1222,7 @@ def main(argv=None):
 
   if command == "change":
     Change(change_info, argv[3:])
-  if command == "description":
+  elif command == "description":
     print change_info.description
   elif command == "lint":
     Lint(change_info, argv[3:])