dmccuskey/DMC-Corona-Library — pull request #6 by krstns (2012-06-29 09:23:02+00:00)
Title: Allow unregistration of not registered listener

Sometimes you want to unregister your listener as part of your game logic, however you also want to make sure your cleanup function removes any touch listeners. In this case you would have to store a flag and mark such touch listener as unregistered.
With this update you can skip this check.