Swain Q is bugged

The bug: When swain's q tether is broken,the damage stops, but the slow continues for the entire duration. Even though it's stated that all of the abilities effects are supposed to end.

http://leagueoflegends.wikia.com/wiki/Swain

" ACTIVE: Swain releases Beatrice, his raven, at his current location to cripple an enemy, creating a tether between her and his target.

Over the next 3 seconds, the target takes magic damage each second and is slowed. If enemies break the tether by moving out of range, the effects end immediately."

This bug makes swain really hard to deal with, even if you're keeping proper spacing between him and yourself.

I hope this gets fixed soon, thanks.