Issue: https://github.com/php/php-src/issues/8218
Comment Author: arcanisgk
It seems to me that there is some kind of confusion; the target of ob_end_clean(); is
to clear the output buffer; but not to clean headers (correct me if I'm wrong); ideally
ob_end_clean(); respect the current header; any data output after
ob_end_clean(); will carry the initially configured header unless it is changed.