We can enable this locally and/or in `brew test-bot` to see if this
code is needed any more. If we can remove it we can start doing much
more interesting things with linking keg-only, versioned formulae and
system dupe formulae.
This is the (partially) documented public API for Homebrew.
The main class you should look at is the {Formula} class (and classes linked from there). That's the class that's used to create Homebrew formulae (i.e. package descriptions). Assume anything else you stumble upon is private.