Martin v. Löwis <martin <at> v.loewis.de> writes:
As for Mercurial, I have been told their repository layout has not changed since their first release and updates have been more about bug fixes and speed improvements.
Speed improvements we can ignore; for bug fixes, it would be good to know how much one can go back without hitting a serious bug (e.g. one that might break the repository).
History of the release notes can be read here: http://www.selenic.com/mercurial/wiki/index.cgi/WhatsNew
From a quick look (and assuming everything is here), there hasn't been any repository corruption bug since 0.9.5, although a couple of crashes are mentioned.