Description:
------------
Using array_search with "haystack" completly numeric and the first 16 digits identic a wrong key is returned. This does not occur if one character is in the "haystack" or if there is any difference in the first 16 digits.

Reproduce code:
---------------
<?
$a = array (11 => "99999999999999999999999999",
            57 => "11022625212002021111111111",
            80 => "11022625212002021051765412");
print_r($a);
$b = array_search ("11022625212002021051765412", $a);
echo $b;
?>

Expected result:
----------------
Array ( [11] => 99999999999999999999999999 [57] => 11022625212002021111111111 [80] => 11022625212002021051765412 ) 80

Actual result:
--------------
Array ( [11] => 99999999999999999999999999 [57] => 11022625212002021111111111 [80] => 11022625212002021051765412 ) 57