Path blocks have ugly lighting when surrounded by blocks

Put the summary of the bug you're having here

What I expected to happen was...:
Pat blocks would look relatively normal when surrounded by blocks

What actually happened was...:
The nice shadowed edges that you have when paths meet blocks all melt together and darken the whole block, which does not look good.

Steps to Reproduce:
1. Build a 3x3 block square of grass blocks
2. Turn the middle block into a path block with a shovel