[GAMEPLAY] Braum - Passive might be refresh after its end

I played a game as Jinx, and my support was a Braum. At a moment, Braum used his Q on ennemy adc (Tristana), which applied his passive. I auto-attacked the ennemy Tristana, Braum's passive was at 2/4. I disengaged, and tried to add one stack a bit later. The Braum passive fell during the travel time of my AA. When I hitted her, the passive just came back, but with only 1 stack. I'm really sure Braum didn't hit her a second time, he was far away, and Tristana was protected by her minions.

I imagine those steps may be effective to reproduce this little bug :

1. Put one stack of Braum's passive on an ennemy.
2. Wait for it to fall.
3. Just before the passive end, use a ranged auto-attack. Try to make it hit after the passive has fallen.
4. Check if the bug appears.

I've seen it only once.