Description:
------------
str_replace does not replace all array values with the associated array replace.

Reproduce code:
---------------
<?php

$string = "test";

test($string);

function test($datei)
{
	$search_s=range('a','z');
	$replace_s=range('z','a');

   	$code = str_replace($search_s, $replace_s, $datei);
		echo $code."\n";
	$decode = str_replace($replace_s, $search_s, $code);
		echo $decode;
} 

?>

Expected result:
----------------
gvhg
test

Actual result:
--------------
gehg 
tvst