I think a generic function, something like `can_retry_except_on_codes` might be useful if we need this in the future?  Although you are correct, I can't think right now of anything we want to do with it.  All the other cases or 404 are handled so far by sticking it in the check for success method.

On the other hand, the specific error about the server being deleted may be useful in this case.

So I dunno, what do you think?  :)