What happens, in fact, is that we don't allow mirrors which have been probed to be deleted.
Also, we now have three different statuses for mirrors (pending-review, official and unofficial) instead of the old official/unofficial ones. Since we now have a list of mirrors pending-review mirrors to see only the mirrors which were not yet reviewed by an admin rather than having them together with the unofficial ones, we may be able to workaround this bug or even make it irrelevant.
What happens, in fact, is that we don't allow mirrors which have been probed to be deleted.
Also, we now have three different statuses for mirrors (pending-review, official and unofficial) instead of the old official/unofficial ones. Since we now have a list of mirrors pending-review mirrors to see only the mirrors which were not yet reviewed by an admin rather than having them together with the unofficial ones, we may be able to workaround this bug or even make it irrelevant.