I think this was working for more than just Hunters. I've been in some bgs lately where I would kite hunter or warlock pets away from their owners or any party members so I could kill it and they keep healing back up over and over without mend/funnel. I have to burst them down within a narrow window of time. This might have been happening "naturally" while the player was attacking someone else and their trinkets proc, or auras/buffs from other players are (re)applying. Maybe this is another bug but it seems like it could explain this behavior I've been seeing lately.