Thread:Extension talk:OpenID/Return to Special:Badtitle instead of the main page after verification has succeeded/reply

This is a sequel of https site and Special:Badtitle

I thought my issue was solved. But things are never so simple. Now my Mediawiki site behaves exactly as described by the first post on this thread:
 * verification succeeds
 * on the Verification Succeeded view the last line displays a link to 'Return to Special:Badtitle.'

I'm unable to figure out what I have done that changed the Mediawiki behavior. The only thing I think about is I purged all the caches of Firefox. I don't know if it can be related.