In this bug there is another problem with the world generation which causes buildings like NPC-villages, dungeons, etc to be generated partly, wrong or even completely not generated. The village for example was once not generated in any way, once with one chunk being 25blocks higher than the others (a field on Y=92) other village part on 65<Y<73, the "hill" was only made of dirt. It was all with the same seed same world parameter setting and on the same windows startup, no differences there.
The dungeons sometimes had no cobblestone before the usual stone blocks come behind the cobblestone (NO CAVE BEHIND MISSING COBBLE)

What I expected to happen was...:
Villages would be generated always the same with same settings and same seed and without mistakes (I know a computer never mistakes, that's why I'm reporting here ); dungeons would be generated completely.

What actually happened was...:
The village is sometimes not generated or with one chunk about 25 blocks higher than the rest. The dungeons sometimes had a hole on where cobblestone must be, there was not a cave behind this but just normal stone, so there would have to be cobblestone.

Steps to Reproduce:
1. Set world attributes to non-default values (ores, biome size etc)
2. Suggesting to use creative mode or other possibilities to move very quick or having the possibility to view wide parts very quickly, generate the world and note down seed and attributes set in 1.
3. Spot a villages or dungeon.
4. Regenerate the world again and again with same attributes and seed (should not be too many times) and go to the buildings until the bugs mentioned above occur.