It would make sense for optimize --upgrade to give the same sort of pristine
repository that optimize --pristine does.
(Maybe even for the former to subsume the latter, but I forget if we had a good
reason to avoid that).
Petr thinks this will be subsumed by the noslurps work (or actually, it
may even be resolved already by that work, in which case we should
update the status of this to resolved)