Heavy shading on water blocks at the world border

When using finite world types, heavy shading appears atop water blocks located next to the world border. There is no apparent effect on underwater fog, and the shading only appears on the the uppermost side of the blocks.
Tested in creative mode with the brightness slider on the lowest possible setting, using pre-0.9.0 worlds as well as the current 'old' world type. This was not present in earlier releases of the game.