#glare

$ grep -r notifications_subscription_list_form contrib
contrib/notifications/notifications.module: $form['#submit'][] = 'notifications_subscription_list_form_validate';
contrib/notifications/notifications.module: $form['#validate'][] = 'notifications_subscription_list_form_submit';
$ 

Submit as validate and validate as submit. This is going to be interesting as I dig into the code.