Convert FormulaLock test to spec.

Convert Mach-O test to spec.

audit: fix revision should be removed.

keg: handle missing alias opt link on uninstall.

keg_relocate: Don't relocate dylib IDs containing metavariables.

Revert "audit: check for version aliases."

Convert SoftwareSpec test to spec.

Convert FormulaPin test to spec.

Convert JavaRequirement test to spec.

Convert OS::Mac::Keg test to spec.

Convert `search_remote_tap` test to spec.

Convert MacOS::Version test to spec.

Convert GPG2Requirement test to spec.

Convert `os/mac/blacklist` test to spec.

Regression introduced in #1754 which meant that (due to storing the
current formula revision in `attributes_map`) `stable_revisions.empty?`
would never be `true`.

Fixes an issue introduced in #1192 where there would be a failure if the
alias link didn't exist on removal (which would be the case for anything
with an alias installed before #1192 was merged).

gcc_version_formula: Use gcc@4.x rather than gcc4x

audit: check for version aliases.

brew uninstal alias for brew uninstall

This will become particularly relevant when there’s a new version of a
formula and the existing alias needs to be removed.

Current version aliases should be provided for versioned formulae so
people can `brew install foo@1.2` to provide pin-like behaviour.

If `brew instal` is permissible, `brew uninstal` should be, too.

java_requirement: Make macOS overrides extend Requirement

This doesn't actually seem to make that much difference,
but it is at least consistent with the main class body and with
the Linux overrides.

Use `alias_matcher` for `fail_with`.

bump-formula-pr: improve duplicate detection

audit: fix insecure mirror check when stdout is empty

Add /usr/libexec/cups to the list of system dirs

Convert Formulary test to spec.