Jumping effect on honey still happens on slabs above it

When jumping on a slab placed on a honey block, it still makes you jump about 0.2 blocks compared to the usual 1.25 blocks.

I think this bug affects 1.15 to the latest snapshot. I'm not entirely sure.

Steps to reproduce:
1. Place down about 5 honey blocks
2. Put any slab on top of all the honey
3. Jump