Wither (when flying) has VERY strange behavior.

When spawning the Wither, its movements become very weird after attacking the player. It starts to fly back and forth to a preferred spot it wants to be at, ignoring everything else. This leaves the Wither VERY open for the player to attack. This phenomenon only occurs if the Wither is above 50%-100% health. I believe this has been going on since the earlier builds of 1.0.