[GAMEPLAY] Gangplank gets slowed after buying upgrade

After buying upgrade gangpank gets slowed to 200 movement speed like in same manner as Nasus' W. (Nasus wasn't even game btw, nobody was near when teleported to base). Maybe some weird interaction with homeguards and upgrading? I'd try to reproduce but spending 15min+ in custom games to test isn't very appealing to me.

1. Buy second upgrade as gp (not sure if Raise Morale or Fire At Will (80% sure it's Fire At Will).
2. Get slowed (look at gp movement speed in video) :)