Description:
------------
php gives the next fatal error:
Fatal error: Allowed memory size of -2147483648 bytes exhausted (tried to allocate 2147221481 bytes) in /root/convert.php on line 6
when trying to use a script with a memory limit of 2gig.

Reproduce code:
---------------
<?php
ini_set('memory_limit', '2048M');
$d = '';
while (true)
{
$d .= 'a';
}


Expected result:
----------------
Fatal error: Allowed memory size of 2147483648 bytes exhausted (tried to allocate 2147221481 bytes) in /root/convert.php on line 6

Actual result:
--------------
Fatal error: Allowed memory size of -2147483648 bytes exhausted (tried to allocate 2147221481 bytes) in /root/convert.php on line 6