when I load up a world in a newer snapshot some of the blocks in that world emits light even when a light source is blocked

*What I expected to happen was...:*I thought is would just be a shading glitch 

What actually happened was...: the blocks were actually emitting light

Steps to Reproduce:
1. make a huge house with no light source but the sun 
2. then load that world with the house u made in the newest snapshot
3. look for the light problem