Somehow http://beta.musicbrainz.org/edit/18161342 managed to create a release group with no name - http://beta.musicbrainz.org/release-group/de65c7fd-1dd2-47e0-8c8a-939257367f67 The edit was only a couple of weeks ago, so this is presumably not a bug we've fixed.
In review at http://codereview.musicbrainz.org/r/2299/
This has been merged into the beta branch, but as these are only database changes there is no beta testing to do, so I am closing the ticket.
In review at http://codereview.musicbrainz.org/r/2299/