I spawned a pig, then put a lead onto the pig. I made the pig go inside the boat again, the lead dropped, but it was still visible on the fence holding to nothing.

What I expected to happen was...:
The lead should disappear from the fence after the pig goes into the boat.

What actually happened was...:
The lead dropped from the fence, but was still visible attached to the fence.

Steps to Reproduce:

1. Spawn pig (or other mobs that can be attached to a lead)
2.  Put a lead at the pig and then attache it to the fence
3. Make the pig go inside the boat
4. Now the lead should be dropped, but still visible on the fence, holding to nothing
5. You can also break only the fence, but then the lead will disappear a few seconds after that