Another painful job:

1. Setup a moodle.net site on local environment to test out registrations
2. Starting with 2.2, try each major reease of Moodle and ensure they al regiser without problems
3. Work out what what needs to happen to trigger a re-registration (I think it happens in cron after some time passes) - and make sure this works - I think its possible that moodle.net tries to prevent you re-registering too much. If so, we should just strip that out.