Sky light not recalculated when blocks placed in air with /fill command

The bug

When blocks are placed in the world with the fill command, the sky light is not recalculated for the blocks below the placed blocks.

How to reproduce

1. Create a new superflat world
2. Go to 0, 0
3. Run

   /fill 0 255 0 63 255 63 stone
   

4. Check the sky light below the filled area
   → It is 15 when lower values should be expected