Fix a regression introduced in PR #8542, which wouldn’t exclude
formulae and casks from stricter style checks properly unless tapped.
This caused `brew audit Formula/formula.rb` to report violations which
were not meant for formulae and casks.
The fix is to add Exclude patterns for formulae and casks in any
`git clone`d tap’s working tree.
Working outside of the productive Homebrew installation makes sure that
the latter doesn’t interfere with development, and vice versa.
It also helps track work in progress, especially if one tends to forget
things.
b36fd8ebd9