I've adjusted test-bot in:
603918939a
to set CI=1 for Jenkins to make future JENKINS_HOME checks unnecessary.
The only `TRAVIS_*` variable we care about is `TRAVIS_SUDO` so whitelist
that specifically rather than passing through loads of others.
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.