Mobs Instantly Die After Falling From a Lead.

Put the summary of the bug you're having here

What I expected to happen was...:
Untie a cow that was dangleing from a lead.

What actually happened was...:
That cow instantly died once it hit the ground

Steps to Reproduce:
1. Tie a mob to a lead and raise him high enough so it dangles.
2. Break the lead.
3. Watch the mob die from fall damage.