Shadows On Water Don't Use Smooth Lighting

Shadows on water do not use smooth lighting even when it's on.

Steps to reproduce:
1) Make sure smooth lighting is on.
2) Put the water_still.png I have provided (the texture is only to make the issue more visible) in a resource pack, and turn on that resource pack.
3) Create a pool of water.
4) Put a square of blocks above the water so it casts a shadow.
Notice that the shadows aren't shaded like they should be with smooth lighting on.