http://musicbrainz.org/edit/14521966 failed because modbot thinks the tracklist was changed.
I think it was this edit: http://musicbrainz.org/edit/14521964 that caused it to fail.
Both edits were created at once via the release editor, so that shouldn't happen.
One for you perhaps.
It's so upsetting for us non automods having to redo tracklist edits 4 or 5 times !!!!
It's upsetting for us having to vote on all these edits so carefully and see such mess in edit histories...
It's upsetting for me to see my code upset people, don't worry I believe the changes to ModBot have mostly fixed this, however:
If you change track artists in an edit release edit, and edit track artists in an edit medium edit, you're probably going to cause a conflict. I don't think this can really be prevented, because you are asking for 2 edits that do 2 different things. If the artist matches the 'change track artists' edit though, no conflict will happen.
I think that's a fair enough optimistic lock fail.