In certain situations, it’s possible to still receive the stream of email notifications to a topic after attempting to Unsubscribe from it.
For one scenario, tried toggling the Subscribe label to Unsubscribe from a topic, and then toggled it back to Subscribe, and posted to the topic. No email notification.
More combinations to test!
There is an incompatibility with BuddyPress apparently, someone over there is itching to have his fix code tested! 🙂