Perl6 bug or not?

gistfile1.txt

am0c@amolap:~/local/pt$ cat MainWindow.pm 
use Listener;

class MainWindow { 
	has Listener $.listener;
}

am0c@amolap:~/local/pt$ cat Listener.pm 
use MainWindow;

class Listener {
	has MainWindow $.app;
}

am0c@amolap:~/local/pt$ cat test.pl 
use v6;
use MainWindow;

MainWindow.new;

am0c@amolap:~/local/pt$ perl6 -I. test.pl 
===SORRY!===
Circular module loading detected involving module 'MainWindow'
am0c@amolap:~/local/pt$