* make sure exit after reset.
* more wide guardian range. We should trap reset_on_interrupt as soon as
we are about to change any files.
* check INITIAL_BRANCH against UPSTREAM_BRANCH
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.