Slim down the existing text and make it more obvious what's happening.
Note specifically how to add it to your PATH to convince people to try
that instead of `brew link --force`.

tests: automatically restore ENV in teardown

Fix installer deleting artifacts if they already exist.

Add internal command to calculate appcast checkpoint.

Cask: cleanups internal stanzas

This was deprecated and had all formulae removed in:
https://github.com/Homebrew/homebrew-gui/pull/52

Remove legacy cask cache instead of migrating.

Suggested by @reitermarkus in
https://github.com/Homebrew/brew/pull/1890#discussion_r97234536, and
then I added the \A and \Z.

bottle: fix regex

A common git environment is now used in all tests, so this is no longer
required.

This will allow the `brew bundle` test to use the default git
environment.

See https://github.com/Homebrew/brew/pull/1890#discussion_r97229473.

Proposed by @reitermarkus in
https://github.com/Homebrew/brew/pull/1890#discussion_r97210285.

I made one slight adjustment of preserving the previous date string in
case anything was relying on it.

I was waiting for confirmation that there wasn't a good reason for these
to be stubbed before I removed them.

tests: clean up file system for all tests

Noted that this is intended for the revision of this formula instead of
rebuild of a bottle.

These locations are now all automatically cleaned up after every test.

These are no longer necessary.

(No longer just integration tests.)

tests: reset ARGV in teardown

tests: clear tab cache in global teardown

tests: enforce `super` in lifecycle hooks