As a medium mob warden will not auto-jump

The bug

As a medium mob warden will not auto-jump.

Steps to reproduce

1. Summon a warden.
2. Try to push it up the hill.
3. Found that it does not auto-jump.

Unaffected medium mobs

1. Llama
2. Trader llama
3. Horse
4. Donkey
5. Mule
6. Skeleton horse
7. Zombie horse
8. Enderman