Ok, doing that was a silly mistake, but it could have been prevented by:
1. excluding the present release from the search result when looking up a destination release title to move the discid to, or
2. not allowing the move to proceed if the original and destination discs are the same, and give the editor an error prompt instead, or if not
3. nothing should happen, ie the edit has no effect.

however, the bum edit i made was allowed to proceed—and the discids were lost as a result.
http://beta.musicbrainz.org/edit/25023171
http://beta.musicbrainz.org/edit/25023178

My bad, but could this be fixed?