Mobs spawn where they should not be able to after using /fill

The bug

Chunks check mob spawning conditions after removing blocks replaced with /fill BUT before re-calculating light levels: therefore, mobs will spawn in what should be broad daylight after /fill-ing a large area

How to reproduce

1. Create a superflat world and stand on the ground

2. Type /fill ~100 ~1 ~100 ~-50 ~1 ~-100 stone

3. Spam /kill @e[type=!player] until most things are dead

4. Type /fill ~100 ~1 ~100 ~-50 ~1 ~-100 air
   You will see hostile mobs spawning around you even when it has sky access.