SSIA.
It's not in the parallel backend, but in the scheduler (scheduler/devices.c). The reason given in CHANGES.txt for this is: - The scheduler's LoadDevices() function was getting interrupted by the SIGCHLD signal handler; now ignore child signals while loading devices. I don't want to re-introduce whatever bug that was.
Fixed package is cups-1.1.17-13.
Closing some bugs that have been in MODIFIED for a while. Please reopen if the problem persists.