Comment 2 for bug 46237

Still thinking this one through, but there are some other issues to consider (this is basically a "Dear LazyWeb" comment):

  * It's insufficient to consider only directly subscribed users as the people who are truly interested in a bug, because bug contacts and assignees are indirect subscribers too

  * In our current mail system, duplicate notifications are batched with any other changes made around the same time, by the same person

  * Even if they weren't clumped together with other changes, our model currently has no way to distinguish one kind of change notification from another