
Makes `tap` re-runnable and unshallows when requested with `--full`. Tapping with a different URL raises an exception. The homebrew/core tap cannot be untapped with `untap` so running `brew tap --full homebrew/core` is now a built-in way to get a full clone of this tap without resorting to workarounds. Closes #17. Signed-off-by: ilovezfs <ilovezfs@icloud.com>