When a chicken tries to look at the player, it moves its head down instead of up.
What I expected was...:
When a chicken looks at you, it should look at the player's head like all the other mobs; like it did before the bug.
What actually happened...:
Chicken looks at your feet.
It's easy to test. Just find a chicken and wait till it looks at you, well at your feet rather.
The screenshot is fairly old, I know, but the bug is still the same and still present.