• Have you followed the guidelines in our Contributing document?
• Have you checked to ensure there aren't other open Pull Requests for the same change?
• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your changes? Here's an example.
• Have you successfully run brew style with your changes locally?
• Have you successfully run brew tests with your changes locally?

• Fix a bug where we were using the non-existent $GITHUB_USER envvar
  instead of $HOMEBREW_GITHUB_USER which exists and is used
  elsewhere in the Homebrew codebase.
• Document the bug where merge PRs don't go green in CI.
• Document how and when we pull bottles and use brew pull --bottle
  and brew squash-bottle-pr, and also how to recover when you
  accidentally publish a bottle.

This is probably easier to review commit by commit?