sub auto : Private {
    my ($self, $c) = @_;

    if ($c->controller eq $c->controller('Login') ||
        ## The following test eventually starts failing 
        ## while running the register controller:
        $c->controller eq $c->controller('Register') ) {
        return 1;
    }
     if (!$c->user_exists) {
        $c->response->redirect($c->uri_for('/login'));
     }
     ...