note 24911 rejected from features.safe-mode by jmcastagnetto

Shame, ignore_user_abort() seems also disabled in Safe mode. And this creates a security issue, because you can't avoid unexpected interruption of your script while performing critical updates in files or in databases without rollback history (such as MySQL)... So the safe mode exposes your site data at risks, as there's no way to guarantee atomic critical operations that should never interrupted in the middle.