Visual rendering issue of the horizon. Appears only in 1.8 Pre and Pre2

Strange blackness on the horizon. I tried with various graphics settings, with both 1.8 Pre and Pre2 and it's there. It don't crash the game of affect it in any other way then being there, annoying and ugly. I'm sure not the only one with this issue. The second screenshot is to show that i don't have the issue in 1.7.10 or any other previous versions.