It seems to me that the built-in .sort uses a randomized algorithm that leads to results that differ from run-to-run when there are elements with identical keys.
This seems like a bad idea to me for the built-in algorithm to have non-deterministic behavior because it means you can have bugs that aren't consistently repeatable. I think the built-in sort should be some kind of stable sort. Also the stability or lack thereof is not mentioned in the spec, and it probably should be because stability is critical for some uses of sorting. One shouldn't have to guess whether a given implementation of D will use a stable sort or not. --bb