Sometimes creating IPP Everywhere printer (temporary or permanent) can fail because the thread was using a pointer from global variable unprotected by a lock, so another thread cleared the pointer's content under the original thread hands.

Upstream issue https://github.com/OpenPrinting/cups/issues/1033
Upstream fix https://github.com/OpenPrinting/cups/commit/313c388dbc023bbcb75d1efed800d0cfc992a6cc