I have no idea also, but with a invalid separator a found $dir was empty on my system for a first iteration.
I could dump my PATH if you are interested.

I also experimenting with a IIS installation, ad if i found any problem/fix i will report it here.

Best Regards

Following fragment of code does not work correctly on a Windows system, problem is that on a Windows system directories inside path variable are separated by ";" and not by ":".

if (isset($_SERVER['PATH'])) {
$path = array_merge($path, explode(':', $_SERVER['PATH']));
}


Fix:

if (isset ...