Showing subscribers to duplicates under "May be notified" is confusing

[Nathan Teodosio]

Let's say bug D is marked duplicated of bug B.

I see that there is a handful of "subscribed to all changes" users in D, but they are listed under "may be notified" in B.

Wouldn't it make more sense to subscribe all subscribers to D to the corresponding category of B?

[Colin Watson (cjwatson)]

They're treated as indirect subscribers; copying the subscriptions over to the duplicate target would mean that if it turned out that somebody had made a mistake in setting the duplicate target then it would be hard to undo that.

I believe that subscribers from duplicates are still notified about changes - have you observed otherwise? Is this just about the way they're displayed in the UI?

[Nathan Teodosio (nteodosio)]

> They're treated as indirect subscribers;

That means that they are actually notified as they normally would for
both bugs, as long as the duplicate status stands?

> copying the subscriptions over
> to the duplicate target would mean that if it turned out that somebody
> had made a mistake in setting the duplicate target then it would be hard
> to undo that.

True, makes sense.

> I believe that subscribers from duplicates are still notified about
> changes - have you observed otherwise? Is this just about the way
> they're displayed in the UI?

I wasn't able to observe the effect myself.

The UI led me to believe that they possibly wouldn't be notified, as
they are then under "may be notified" (which is not very clear of
itself, I assume that category is for users under more specific
notification rules, but that's another topic).

[Colin Watson (cjwatson)]

They are actually notified, yes. I suspect that it might be this way due to performance issues with accurately working out the subscribers when rendering the bug page (though I haven't positively confirmed that - it might require some trawling through history), but I agree it's still confusing UI.