If there is a bad patch deployed that needs to be reverted immediately, the revert is more important than the checks for php-fpm's cache ensuring server capacity for serving... HTTP 500 errors.
Original plan: Using the flag should Just Work™ and deploy as fast as possible for all scap sync-* commands.
Updated plan, per T243009#6527973, when the flag is set, we should do an immediate local restart of php-fpm, instead of the graceful depool/restart/repool script. It should use the same rolling batch mechanism as the regular restart, which should be fast enough.