If a relationship is added (to a work, for example) [1] and then the related entity is merged [2], the related entity is displayed as "has been removed", and presumably the edit will fail due to one of the related entities being gone. It would be a lot nicer if the edit would track the merge, and thus point to the destination of the merge. (in this case it would still fail due to the relationship already existing)

1. http://musicbrainz.org/edit/14473794
2. http://musicbrainz.org/edit/14472152