Huh! So, before I posted this, I went to go double check, and found https://wiki.freebsd.org/VersionControl. What I missed was the (now obvious) banner saying

> The sections below are currently a historical reference covering FreeBSD's migration from CVS to Subversion.

My apologies! At the end of the day, the point still stands in that SVN isn't a DVCS and so you wouldn't want to be committing unfinished code though, correct?

(I suspect I got FreeBSD mixed up with OpenBSD in my head here, embarrassing.)

You could still use git-svn, but yeah, as another commenter wrote, I don't think reproducible build is that useful when debugging, it should be fine to have an actual timestamp in the binaries.

Well yes, but we've actually migrated to Git now. ;-)

Welp! Egg on my face twice!