I was playing minetest with some friends today, and we came across what appears to be an interesting bug.
From the top of a mountain, we could see normal-looking terrain in front of us: just standard mountainous ground with trees. When we got closer, however, a section of the map in front of us appeared to change completely. The area used to be ground, but it was now a pit filled with water. It basically looked like the server generated normal terrain, but it then regenerated a section of the map and spliced it into the existing map. The result is best demonstrated with images:
[img=Img1]http://img714.imageshack.us/img714/8291/minetestregeneratedchun.jpg[/img]
[img=Img1]http://img69.imageshack.us/img69/8291/minetestregeneratedchun.jpg[/img]
You can pretty clearly see that this section does not look normal - especially when you look at how the trees/leaves are cut off.