Quote from Skylinerw
Mhm, I'm really impressed with the dramatic change. Unfortunately it comes with some minor bugs, so be sure to report them to Jonk: https://twitter.com/#!/jonkagstrom. I've got a showing a few quirks about their AI, namely their behavior in water. If Jonk doesn't fix that, then water could be used defensively against mobs in some manner (not that it couldn't before, but it seems to utterly wreck their new pathfinding).
I think in a recent snapshot their pathfinding was changed to make them sink in water, so it's understandable it messes up their AI to a degree. But I think it's a welcome addition, as now it's going to hard enough to avoid a zombie on land, let alone in water. (If I'm wrong about the me sinking in water, let me know). It would be good to have some relief by dipping into some water.