Previously if a `brew reinstall` was Ctrl-Cd after some files had been
installed it wouldn't try to remove the partially installed keg and the
renaming of the backed-up keg would fail. Alternatively, remove the
partially installed keg as if it has been Ctrl-Cd or otherwise failed
then it's not desirable to keep it.
This requires updating to Rubocop 0.49.0 which will require some fixes
to rules, in Homebrew/brew and Homebrew/homebrew-core but opening this
for now so I remember.
Improve the messaging around `brew install` when there's a possible user
action such as an `upgrade` or `link` and don't tell people to
`install --force` when it's unnecessary.
While I did this, tweak the output and function usage in a couple of
related places.
Some example output before this change:
```
Warning: openssl is a keg-only and another version is linked to opt.
Use `brew install --force` if you want to install this version
Warning: mysql@5.6 is a keg-only and another version is linked to opt.
Use `brew install --force` if you want to install this version
Warning: analog-6.0_1 already installed
Warning: bash-completion@2-2.5 already installed, it's just not linked.
```
Some example output after this change:
```
Error: openssl 1.0.2k is already installed
To upgrade to 1.0.2l, run `brew upgrade openssl`
Warning: mysql@5.6 5.6.36_1 is already installed
Warning: analog 6.0_1 is already installed
Warning: bash-completion@2 2.5 is already installed, it's just not linked.
You can use `brew link bash-completion@2` to link this version.
```
Homebrew's actually ended up using a fair few gems. While we want to
avoid Bundler at runtime (and this PR still does that, in fact uses
Bundler even less at runtime than it did before) writing our own version
to use at build-time seems redundant.
Also, don't delete them after that. This means that `brew postinstall`
becomes a way to easily reinstall configuration files for any formula
without needing any changes to any bottles or requiring a reinstall.
On Linux this defaults to Linuxbrew but in some cases (i.e. a Linux
machine performing uploads for Homebrew) we want to allow this to be
overridden back to the defaults.
Relies on a change incoming to `brew test-bot` to set this there.
Use GitHub's code search API to search using the filename based on the
search query. This means we only need a single HTTP call and no more
multithreading madness. This also means we're able to search everything
in the Homebrew and Caskroom organisation by default without having to
maintain a list of things to search (and not) in here.
Deprecate more methods. Internal APIs have been verified to be unused
elsewhere and removed. External APIs have had deprecation methods added.
Existing deprecations have been either upgraded to produce warnings or
no longer deprecated and the reasoning documented.
