Description:
------------
If you access a script by a name other than its filename, it generates a Content-Location HTTP header. For example, if you request '/a' instead of '/a.php', the Content-Location header contains 'a.php'.

If you try to override the Content-Location header in the script, like in the code example below, the response contains two Content-Location headers.

Reproduce code:
---------------
<?php
header('Content-Location: http://www.example.org/a.php');
?>

Expected result:
----------------
One Content-Location header in result:
Content-Location: http://www.example.org/a.php

Actual result:
--------------
Two Content-Location headers in result:
Content-Location: a.php
Content-Location: http://www.example.org/a.php