Runeglaive can't destroy Teemo Shrooms

So the first time it happened I shrugged it off because it was in normals but the second time I was in ranked and it was a whole two patches later and it's still not fixed. If you have spellblade passive on with Runeglaive you have to wait until you can destroy it... Which fucked me over a couple of times. Invulnerable mushrooms are stupid... And scary.