OK, I'm trying to work out what's going on here.
Line 44 checks the existence of the authtype class file, and then loads the basic class and then the authtype class. This succeeds.
Line 49 checks the existence of the class $auth_class and this also succeeds.
Line 50 creates a new class:
$auth = new $auth_class();
This is checked in line 51:
51 if ($auth->success == false) {
This loop is triggered 'cause $auth didn't success, and the process degrades. But why does this fail? Am I reading it correctly, that PHP is failing to create a class long before the ACL file is loaded?