Edit relationship fails with internal error when attempting to move credits between recordings

see:
http://musicbrainz.org/recording/8abba0c4-7037-4ca6-bb80-388126fe11f3 (where incorrect 1993 conductor and orchestra credits presently are)
http://musicbrainz.org/recording/e8ae14e9-db39-4365-b7e9-dd4770927e36 (where they should actually be moved to)

i've made multiple attempts to move the credits w/o successful; the failed edits just loop the credits back to the current recording: http://musicbrainz.org/recording/8abba0c4-7037-4ca6-bb80-388126fe11f3
http://musicbrainz.org/edit/15352251
http://musicbrainz.org/edit/15352226
http://musicbrainz.org/edit/15352190
http://musicbrainz.org/edit/15352177
when i had already changed (and verified) the link to the new recording: http://musicbrainz.org/recording/e8ae14e9-db39-4365-b7e9-dd4770927e36