Grass block turns into dirt if there's at least two snow layers on top of it

The bug

Grass blocks turn into dirt when there's at least two snow layers on top of it.

To reproduce

1. Place a grass block
2. Place two snow layers on top of it
3. Wait (or use /gamerule randomTickSpeed if you're impatient)
4. The grass block turns into dirt

Original description

Light used to go through snow layers, but doesn't anymore. Also, when placing more than 1 layer on a grass block the game removes the grass from the dirt.