bugfix for when file is called from another path

[elitan]

file_exists() does not work as expected when config.php is included from another path. From upgrade/ for instance.

[ext]

Do you get an error without this? Most of the time PHP searches relative to the current file (in addition to a few other locations). What platform and versions?

The patch has the (nasty) side-effect of changing the working directory.

I would rather suggest something as following:

$basedir = dirname(__FILE__);
file_exists("$basedir/...")
require("$basedir/...");