Ref T12942. Currently, we have a bunch of code spread out all over the place for doing version tests on hg, svn, and git.
Consolidate this code a bit so we can use it to drive a new section on the "Version Information" page showing the installed versions (and paths) for binaries.
The primary goal is to reduce the support burden a little bit. Two particular issues are:
- Various stuff with old (or new) VCS binaries, mostly Mercurial.
- Cases where the webserver sees a different binary than sudoers specifies.
These should be easier to spot with binaries in the version info.