- Use constants for placeholders
- Monkeypatch to set `HOMEBREW_PREFIX` consistently to placeholder
- Use environment variable to set `Dir.home` consistently to placeholder
- Use `appdir` short-circuit to set `Cask#appdir` consistently to placeholder
- Use `Cask.generating_hash!` to enable "generating mode" with these patches
- Fix `Formula#caveats` from JSON
Fixes#14505Fixes#14595
