Mobs hanging on an edge of a block while being pushed with water.

See the video I uploaded to dropbox to show what is happening. In the video I recorded iron golems being spawned and not falling into the lava, but instead hanging over the lava barely by its hitbox.

 

https://www.dropbox.com/s/8vgauksxk5jpp0v/Mobs%20not%20falling%20in%20water.mp4?dl=0