Description:
------------
There appears to have been a regression to bug 37476 which was 
apparently fixed way back in php 4.2 ?

Reproduce code:
---------------
<?php
ini_set('include_path',ini_get('include_path').':lib/php:');
$file = 'test.php';
if (file_exists($file)) {
require ($file);
}
?>

Expected result:
----------------
File lib/php/test.php should be included

Actual result:
--------------
"file not found"