[Gameplay][Champion] Amumu ult bug

Was playing the above ARAM game when I noticed this bug: Amumu's (me) able to use his ult, and if done so at the last possible moment before death, the runes stay on the ground and it never goes on cooldown. After this game, I went and tested this in the practice tool and managed to recreate it. I'd say it's a rare bug, since it needs some timing to pull off, but it's still powerful to enable a 200s+ ult to come back immediately.

Method for reproducing: Enter a game, wait until level 6 (or use the practice tool and get to 6) Wait until about to die, last possible moment hit your ult

So far, it's pretty consistent if done when the attack/turret shot/ability goes off seemingly at the same time (or frame) amumu dies. As much as he loves hugging people, death hug should not mean he gets to double hug.