Description:
------------
When using file_get_contents, the function only seems to include HTTP Authentication data when the password is set. When no password is set (e.g. http://username@myurl.com), no authentication data is sent. The result of this is, when calling another PHP script with file_get_contents and only supplying an HTTP username, $_SERVER['PHP_AUTH_USER'] is (unexpectedly) not set.

We are using Apache 2.2 in this setup (for server.php).
$_SERVER['PHP_AUTH_USER'] does seem to be set when calling the same URL using cURL or a browser.

Reproduce code:
---------------
client.php:
<?php
echo file_get_contents('http://testusername@hostname.tld/server.php');
?>

server.php:
<?php
if (isset($_SERVER['PHP_AUTH_USER']))
{
    echo $_SERVER['PHP_AUTH_USER'];
}
else
{
    echo "PHP AUTH USER not set";
}
?>


Expected result:
----------------
USER: testusername

Actual result:
--------------
PHP AUTH USER not set