Chickens and smaller animals, such as baby cows take damage if under blocks that are on top of fences.

What I expected to happen was...:

I expected that the smaller animals, such as chickens and baby cows could walk under a block that stands on top of a fence, without the animals taking damage.

What actually happened was...:
What actually happened was that chickens of all sorts and also baby cows sometimes take damage when standing under a block with a fence under it.

Steps to Reproduce:
1. Make a 5x5 platform of dirt.
2. Put fences on top of all of the edges and corners of the dirt platform.
3. Put plank blocks of any sort on top of all the fences.

4. Spawn in 20-25 chickens inside of the fences.

5. Watch the poor chickens take damage at times while standing under the edges of the plank blocks.