Graphic textures bug

I get texture bug: it seems that the blocks are separated by a blank line from a certain vue.Sauf for water lines are purple, it makes the game less beautiful.
The bug is in the snapshot 12w49A and 12w50. But I use the default textures and even with other texture beug this place.
If the images do not convince you I can make a video, the rendering is really horrible.
Sorry for my pathetic English.