Description:
------------
The readline() function always tab completes the filesystem even if a custom completion function is used.  This behavior is undocumented and undesirable in some applications.

Reproduce code:
---------------
<?
    readline_completion_function("complete");
    readline("> ");

    function complete($line, $pos, $cursor)
    {
        return array();
    }
?>


Expected result:
----------------
I expect nothing to happen when I press tab.

Actual result:
--------------
The filesystem is completed as with bash.