I have fixed the disappearing queue problem upstream in commit dd862c9b.
What happened is that one cannot reliably determine the temporary nature of a CUPS queue via printer-is-temporary. So I check whether the queue is shared instead and as any shared queue is permanent I do the procedure of setting and unsetting the shared bit on any unshared queue as it can be temporary. So with this I am sure that my queue is permanent and I do not interrupt the shared status of a shared queue.
Till
