brew/Library/Homebrew/requirements, branch 1.5.6

xcode_requirement: handle nil @version.

2018-02-09T19:37:15+00:00

When the Xcode requirement doesn't specify a version then we need to
guard this check.

xcode_requirement: inform users of macOS upgrade.

2018-01-28T19:08:19+00:00

If you need a newer Xcode than the latest version provided by your
version of macOS then you need to upgrade your OS to install the
software.

requirements: move more to compat.

2017-12-30T20:56:55+00:00

Deprecate more requirements.

2017-12-23T16:53:25+00:00

These are ones that were either already deprecated due to audit rules
or are just a simple `which` with a `default_formula` so should just
be a dependency.

java_requirement: use popen_read :err option.

2017-12-14T16:44:25+00:00

python_requirement: various tweaks/fixes.

2017-12-14T09:21:26+00:00

- simplify the code by avoiding some unnecessary variables and rename
  functions
- make more stuff private so implementation details don't leak
- make Python 2 binary `python2.7` to handle cases like those in
  https://github.com/Homebrew/homebrew-core/issues/21500
- only set `PYTHONPATH` for system Python; Homebrew's Python doesn't
  need it.

Implement X11Requirement for Linux

2017-12-07T16:45:29+00:00

Move the XQuartz implementation to extend/os/mac/requirements.

x11_requirement: remove custom minimum version.

2017-12-03T13:33:16+00:00

This isn't desired or needed. Ensure older code still works, though.

gpg2_requirement: use direct 'available?' logic

2017-10-22T04:11:52+00:00

Use “squiggly” heredocs.

2017-10-18T12:39:09+00:00