[#81628184] User is added as participant when commenting

When you add a comment, if you are not a participant you are added as a participant (assuming you have the permission to comment). Also, your avatar will appear in the list of participants after commenting (thanks event stream!)
I wonder whether `unless comment.task.participants.include? current_user` would be better here? It feels more natural to me. Also, `current_user.tasks` could potentially be a large list to go through in the comparison, while `comment.task.participants` would be smaller.