The crashdump file compresses pretty nicely, actually, using 7z or rar on it could have reduced it easily to a third of that size. But whatever 
I am officially crazy. I solved this bug yesterday at night. While sleeping. In a dream. Totally weird. But when I woke up and went through the sources, the solution that I came up with in the dream seems right. The detailed crashdump confirms it. Unbelievable.
Your hint that the crash doesn't happen too often was the first lead. The crashing line was the second. It's rather simple - the random generator generated too large a number, and when we added an existing coord to it, it overflowed, causing a (very) negative coord to be used, thus accessing memory outside of the chunk data.
Fixed in Rev 533.
I am officially crazy. I solved this bug yesterday at night. While sleeping. In a dream. Totally weird. But when I woke up and went through the sources, the solution that I came up with in the dream seems right. The detailed crashdump confirms it. Unbelievable.
Your hint that the crash doesn't happen too often was the first lead. The crashing line was the second. It's rather simple - the random generator generated too large a number, and when we added an existing coord to it, it overflowed, causing a (very) negative coord to be used, thus accessing memory outside of the chunk data.
Fixed in Rev 533.