The lower part of the sky gets darker when you're in a dark spot

Since 13w38c, no matter what video option you pick, standing in a spot with light level below 15 makes the sky near the horizon darker, the lower the light level, the darker the sky gets.

It used to do that before but only at render distance below Normal, now it happens at any render distance. The 2 pics were made at render distance 12 and Normal respectively.