If you hover in spectator 1 block above a slab then go to survival, your head and legs glitch through the slab then under it

Normally if you hover over a solid block 1 block above it in spectator then switch to survival, your legs are in the solid block and your head sticks out and does not glitch through.

You glitch through the slab and end up underneath it.

Steps to Reproduce:
1. find a flat area and build 5 blocks in the air and place a top half slab.
2. In spectator mode hover 1 block above the slab.
3. Switch to survival mode and you will glitch through the slab and end up underneath it.