strange black line across the horizon

when I play on the new pre release that was just released I get this really strange thick black line across the horizon that will not go away no matter how much I change settings(see Picture). I haven't had this issue on any other versions of minecraft including 1.7.10. It has really only started this since the stuff leading up to this update as well as this update http://puu.sh/b3guK/5fc5464eae.jpg