Description:
------------
The documentation page for the header() function (http://www.php.net/manual/en/function.header.php) doesn't officialy state that setting headers in this manner:

header('Cache-Control:');
header('Pragma:');

will prevent those headers from being sent even if previously set. Ie. it will efectively delete the headers.



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

session_cache_limiter('nocache');
session_start();
header('Cache-Control: max-age=10000');
header('Pragma:'); // deletes "Pragma: no-cache" set by
                   // session_cache_limiter
header('Expires:');

?>