Code relative filepaths to webroot cause JS 403 error

Hi, noticing a strange bug since version 1.8.4. My custom theme code includes the following:

require ‘../../../wp-config.php’;

Before 1.8.4 this would save fine. However, now when I make any edits to the theme file containing this code, it won’t save and shows a Javascript error: Unable to connect to backend. Access denied. Error 403.

After much troubleshooting, I’ve determined the issue is with Filester. These variations work fine:

• require ‘../../my-file.php ## not in web root
• require ‘../../wp-confug.php ## file doesn’t exist and not in web root

However, these all cause the error:

• require ‘../../../wp-config.php ## in web root
• ## require ‘../../../wp-config.php ## even commented code fails b/c it has web root path
• require ‘../../../my-file.php ## in web root
• ## commented code that contains path to web root like this ../../../my-file.php

A hack workaround is to convert the file path to a variable like this:

• $path = ‘../..’;
• $path.= ‘../wp-config.php’;
• require $path;

Please take a look and hopefully you can find the fix. Thank you!