Description:
------------
preg_match fails to return result matches in case matches variable gets assigned a value in function call statement.

Reproduce code:
---------------
<?php
preg_match('/\wte/', 'teste', $m = array());
var_dump($m);
?>

Expected result:
----------------
array(1) {
  [0]=>
  string(3) "ste"
}

Actual result:
--------------
array(0) {
}