fall damage gets negated/reduced

Steps to Reproduce

1. place a boat on a high edge
2. hook an entity
3. ride the boat
4. make the hooked entity also ride the boat
5. ride off the edge
6. unhook the entity (in air close to ground)
7. dismount (in air close to ground)

Observed Result
No fall damage is received

Expected Behavior 
both entities die of fall damage

video https://www.youtube.com/watch?v=hsXALKLg8zg