'Trap Vision' items temporarily lose vision of Teemo Shroom/Shacobox when transitioning to invis

I haven't checked this in 6.7, but before 6.6 if you had Sweeper or lightbringer item that allows you to see traps and a trap is placed in your vision circle, it temporarily disappears. This means you stop attacking and can fool hardidly run over it.

Steps to repro:

1. Buy a Hextech sweeper in aram (play against a teemo)
2. Have teemo put a mushroom within your 'vision circle'
3. Let it disappear.

Result: It disappears and then reappears. It should never disappear as you have a vision item.