What I expected to happen was...:
A Chicken spawned with a Baby Zombie riding it should lay an egg as it usually does.
What actually happened was...:
The Chicken does not lay eggs.
Steps to Reproduce:
1. Find a Chicken Jockey (Mine spawn from a Spawner in a Mushroom Island, in case this information is relevant.).
2. Get rid of the Baby Zombie riding the Chicken.
3. Wait around the Chicken and observe how it doesn't lay eggs.