Right now when somebody subscribes to an updates in a task a non human-friendly message is added in task activity history and e-mailed to all other subscribers:
aklapper added a subscriber: aklapper.
{F150867}
I think it will be better to write aklapper added himself/herself as a subscriber. for cases when user is subscribing. The phrasing is to be kept as is when UserA is subscribing UserB for example.