Ensure the full HOMEBREW_TAP_DIR path is created before deleting and
creating the symlink for it. This ensures that non-`homebrew` taps will
have the necessary username/organisation folder created.
Fixes#2378.
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.