The GNU Autotools tests for whether futimens and utimensat are available
reliably come to incorrect conclusions on 10.12 with the 10.13 SDK in
Xcode 9. This overrides its decisions by forcing the right answer
in superenv using ac_cv_func_* environment variables and setting them to
"no" on 10.12.
`brew cask list` supports the `--full-name` flag which will include the tap
name for casks not part of the core caskroom/cask tap. For example, if
cask "foo-beta" is installed from the caskroom/versions cask, `brew cask
list --full-name` will report the name as "caskroom/versions/foo-beta".
Previously .lai files only had their locations replaced with
placeholders if /usr/bin/file recognized them as ASCII files, which is
only the case on macOS Sierra and above.
- `brew update` should try to install `curl` before `git` on older
versions of Mac OS X where it is needed for accessing modern SSL
certificates.
- We don't need an HTTP mirror for `git` because `curl` will already be
installed before it is downloaded.
- Don't recommend GCC on Mac OS X versions where it can't be built with
the default system compiler.
- Start using the Homebrew `curl` on Mac OS X versions where it is
needed as soon as it is installed.
This avoids `brew doctor` warnings on High Sierra but in general this is
a good idea for future versions and to allow Homebrew developers to test
things out with different versions of Ruby.
This allows the bootstrap of `curl` and `git` on versions of Mac OS X
that cannot reliably download from HTTPS servers any longer. Once these
are both installed users are able to update Homebrew and download files
securely.
Also, as we're doing this, don't point 10.5 users to Tigerbrew as they
are already given caveats for using Homebrew itself.