Description:
------------
If you throw an exception inside an output_callback function as a result of using ob_start() and ob_end_clean(), a Segmentation fault occurs.


Reproduce code:
---------------
<?php
function output_handler($buffer)
{
	throw new Exception;
}

ob_start('output_handler');

ob_end_clean();
?>


Expected result:
----------------
Exception is thrown.


Actual result:
--------------
Segmentation fault