brew style: assume file args are non-formulae when passed --rspec

brew.sh: enable linkage cache for developers.

bump-formula-pr: don't unset --mirror= value

rubocop: exclude .simplecov under vendor

Refactor `.simplecov`.

remove appcast checkpoints

Bump rspec-retry from 0.6.0 to 0.6.1 in /Library/Homebrew/test

Bumps [rspec-retry](https://github.com/noredink/rspec-retry) from 0.6.0 to 0.6.1.
- [Release notes](https://github.com/noredink/rspec-retry/releases)
- [Changelog](https://github.com/NoRedInk/rspec-retry/blob/master/changelog.md)
- [Commits](https://github.com/noredink/rspec-retry/compare/v0.6.0...v0.6.1

)

Signed-off-by: dependabot[bot] <support@dependabot.com>

brew style zsh completion: complete files

This seems stable on CI so I think we can expose it to more people.

Support constants in `DependencyOrder` cop.

Add `stderr` output to exception.

Remove `Hbc.init`.

fix typo

formula_installer: don't pass spec arguments from ARGV to postinstall

text_cop: require cargo to use `install` instead of `build`

Postinstall should be executed with the spec of the target formula not
the spec argument from ARGV, otherwise the prefix can be incorrect. In
other words, if the stable version of a dependency gets installed,
postinstall for the dependency should use the prefix of the dependency's
stable version, not the prefix of its devel or head version.

Fixes #2941.

Remove `Locations` module.