This bug seems to have appeared in 15w35a, as attempting to reproduce in 15w34d does not lead to any results. The bug seems easy to reproduce. All that's required is to open/generate a world in at least 15w35a, and, at any time, save and exit. The amount of chunks generated may not be relevant. Then reload the world. Chunk rendering will act confused in a way that is hard to describe, but your actual location and the blocks nearby remain the same. This also seems to affect some mobs as well, distorting their models and sizes. I've noticed this with slimes, pigs, horses, chickens, and spiders, and presumably a few more. This part is actually somewhat interesting as Creepers are not touched by the bug at all.

EDIT: Curiosities have arisen when I attempted to duplicate it with a default superflat world. The default doesn't work but the Overworld preset does. More testing might be required. Also, the mobs that are affected seem to be completely random;