Description:
------------
When mb_ereg is passed certain data types as the $pattern argument it will return int(1), i.e. a successful match, when in fact it has not matched. This is shown by setting the $regs argument and looking at the returned array which only contains one element which is bool(false). 

Reproduce code:
---------------
<?php
$unset_var = 10;
unset ($unset_var);
$inputs = array(NULL, null, false, FALSE, "", '', @$undefined_var, @$unset_var);

$iterator = 1;
foreach($inputs as $input) {
	if(@is_array($mb_regs)){
		$mb_regs = '';
	}
	echo "\n-- Iteration $iterator --\n";
	echo "Without \$regs arg:\n";
	var_dump( mb_ereg($input, 'hello, world') );
	echo "With \$regs arg:\n";
	var_dump(mb_ereg($input, 'hello, world', $mb_regs));
	var_dump($mb_regs);
	$iterator++;
};
?>

Expected result:
----------------
http://pastebin.com/f5f5c20ff

Actual result:
--------------
http://pastebin.com/f3f966bd0