For now this goes undocumented. The trouble with rewind is:
1. To rewind we need to reset all repositories. That only really
works on top of the current branch. Possible solution: only
allow rewind for the currently up-to-date version.
2. The master branch development version is in the way and will
probably prevent people from building older versions because
of this or that mismatch. Possible solution: allow a build
without development packages included and maybe default to it.