Description:
------------
$_SERVER['PHP_AUTH_USER'] does not pass the parameter to header.  This same problem was reported and was supposed to be fixed on version PHP 5.0. Now, it happens again with Zend Server CE (PHP 5.3.1).

Reproduce code:
---------------
<?php
if (!isset($_SERVER['PHP_AUTH_USER'])) {
    header('WWW-Authenticate: Basic realm="My Realm"');
    header('HTTP/1.0 401 Unauthorized');
    echo 'Text to send if user hits Cancel button';
    exit;
} else {
    echo "<p>Hello {$_SERVER['PHP_AUTH_USER']}.</p>";
    echo "<p>You entered {$_SERVER['PHP_AUTH_PW']} as your password.</p>";
}
?> 

Expected result:
----------------
After entering username and password, the username and password will be displayed on the web page.

Actual result:
--------------
In IE, the authentication window will ask 3 times for username and password.  Then, it closes, and displays "Text to send if user hits Cancel button."  In Firefox, it keeps asking for the username and pssword.