We have some exceptions to disable Speed Booster (Nginx cache) on the fly on some requests which shouldn't be cached to avoid issues, typically for various AJAX calls, upload progress etc. Unfortunately, only exceptions where
$expire_in_second > 0 work, while
$expire_in_second == 0 never works, because we are using incorrect check:
!empty($expire_in_seconds) to determine if we should send the special header or not.