Delete pkgutil directories that are really files.

Remove `TestCask` class.

formulary: handle ScriptError in formula

Use array of constants to set up test directories.

Proposed fix for "Failed to eject" errors with DMGs

Allow overriding `MacOS.version`.

I added a new `FormulaUnreadableError` subclass of
`FormulaUnavailableError` so existing `rescue`s of
`FormulaUnavailableError` handle this as well.

The new subclass will output the name of the formula with the error
(because this isn't always obvious from the original exception message)
followed by the original error message.

Fixes #1927.

cask: staged: no sudo in set_permissions

Try "diskutil eject" twice before "diskutil unmount force".

update: note migrations may be performed.

cleanup: consider version_scheme

`brew cleanup` should cleanup formulae which have the older
version scheme.

Don’t use `assert_nil` in `tab_test`.

*/Gemfile*: remove rake, version pins, master simplecov.

As requested in https://github.com/Homebrew/homebrew-core/issues/9316.

Rubocop 0.47.1

Update brew-cask.1.md to include _stanza internal command

Revert "formula_cellar_checks: check for prefix/etc."

pull: better handle missing bottles.