Urgot's Purge targets allied Gangplank Barrels.

My Plays.TV unfortunately failed to record the match that I found the bug in (and have no friends who play the game anymore to help out), but in my ARAM as Battlecast Urgot, I noticed that Purge was targeting my allied GP's barrel in a fight. I asked him to throw out a barrel for me so I could test it directly just to make sure I wasn't seeing things, and sure enough Purge shot that thing to hell and back for whatever reason.

I don't think it's a bug to be worried about since I think barrels are low enough in priority for Urgot to attack minions over them, but who knows. Maybe one day that match will come where yu really need to kill off that raging Tibbers before he gets revenge, only to walk next to your pirate buddy's favorite makeshift chair and shoot it up instead like it said mean things about your mother.