Description:
------------
Under very certain circumstances a call-by-reference gets out of bounds. A cascaded call of functions, where one of them has a call-by-reference in its parameters, a change to a copy of an hash gets unexpectedly overwritten outside of its scope. Key to this behaviour is the use of the switch-statement in the final function call.

Additional Information:
- casting the switch-parameter to string solves the problem
- changing the switch into an if-statement also solves the problem

Test script:
---------------
<?php
function a ($option) {
        b($option['bla']);
        c($option);
var_dump($option);
}
function b (&$string) {
        $string = 'changed';
}
function c ($option) {
        switch ($option['bla']) {
                case 'changed':
                        $copy = $option;
                        $copy['bla'] = 'copy';
                        break;
        }
}
a(array('bla' => 'fasel'));

Expected result:
----------------
array(1) { ["bla"]=> string(4) "changed" }

Actual result:
--------------
array(1) { ["bla"]=> string(4) "copy" }