Chickens from chicken jockeys despawn as if they were a hostile mob

What I expected to happen was
that the baby zombie would despawn and the chicken would stay

What actually happened was
the chicken despawned too

Steps to Reproduce:
1. Spawn a bunch of zombies until you get a chicken jockey.
2. Get far enough so that any hostile mob would despawned.
3. Get back and see that the chicken despawned too.