Skeletons At Full Health Die When Set On Fire 1.9 Pre-1

What I expected to happen was in my skeleton xp farm I have a machine setup to activate a dispenser filled with lava allowing the player to one hit kill the skeleton once the skeletons finish burning.

What actually happens now in the 1.9 pre-release 1 is that the skeletons die once set on fire making the xp farm useless.

To reproduce, set a skeleton on fire with a touch of lava. The skeleton will lose all its life.