https://bugzilla.wikimedia.org/show_bug.cgi?id=62126
--- Comment #5 from John Mark Vandenberg jayvdb@gmail.com --- The error we should not resubmit is 'wikibase-error-label-not-unique-item'.
The only error we should retry is 'edit-already-exists'.
That code and my pseudo-code above do the same thing, in different ways.