When was it patched?
Why do you want to know so bad?
And I can say FOR SURE it has never been that way. Like I said coop kills and player kills are the same in that mode. If it counted to kdr it would have been a known abuse and lots of players would get high kdr's there.
You won't get a really high K/D in that mode.
Yes you do if what you say is true. The kills at the leaderboard in coop hunter are both player and AI kills. And its easy to take down 10 or more AI's before you die. And of course it never counted for kills stats but you say it did for some reason.