Sources is not kept up-to-date by volunteers, unless you mean contrib, it is maintained by the Labs. Also, in a way, the sources server *is* Plan 9, rather than being updated *with* Plan 9.
Plan 9 doesn't traditionally use version control. Rather, most disk-based Plan 9 file servers offer some form of history in the form of dumps or snapshots. 9fs sourcesdump will mount the sources dump, and you can inspect daily changes starting around some 12 years ago using regular Plan 9 tools such as editors, yesterday(1) and diffy(1). History management is superior in Plan 9 compared to git and mercurial. What git does better (at least according to some people), is patch management. The Labs and 9atom use some patch management technology best described in their manuals rather than on the mailing list. 9front uses mercurial for patch management. -- Aram Hăvărneanu
