SQLite itself is hosted on fossil, as is Tcl/Tk as you mention (and it's various satellite projects), and I know NetBSD was flirting with it too (no formal decision made yet on migrating from CVS afaik). I use fossil for all of my personal projects. It's more than capable, and a
joy to use. Everybody should try it for a week.
http://www.fossil-scm.org/