Use git_branch_name_using_HEAD instead of git_branch

[oguzkocer]

What does it do?

We have been using git_branch helper action to check if we are on a release branch during complete code freeze & finalize release steps. This has been working as expected in our local environments. However, the return value of this helper can be modified by environment variables such as GIT_BRANCH or BUILDKITE_BRANCH. That means, if we switch the git branch during a CI step, it'll not return the value we are interested in.

There is a Fastlane::Actions.git_branch_name_using_HEAD helper method we can use, which is exactly what we expect. git_branch method actually wraps its implementation around this helper and adds the extra capability of modifying the return value with environment variables.

We have 2 different approaches to address this issue.

1. As implemented in 918027b, we can directly use Fastlane::Actions.git_branch_name_using_HEAD everywhere we need. The main issue with that is, we need to add a disclaimer about why we are using this method instead of git_branch.
2. As implemented in 7669604, we can add a method to git_helper. I like this better because we can have a longer explanation and contain it in a single place. I think this also makes it more likely that we'll use it instead of git_branch when we need to use it somewhere new - although neither option can guarantee that.

Checklist before requesting a review

• Run bundle exec rubocop to test for code style violations and recommendations
• Add Unit Tests (aka specs/*_spec.rb) if applicable
• Run bundle exec rspec to run the whole test suite and ensure all your tests pass
• Make sure you added an entry in the CHANGELOG.md file to describe your changes under the approprioate existing ### subsection of the existing ## Trunk section.

[spencertransier]

I like this better because we can have a longer explanation and contain it in a single place. I think this also makes it more likely that we'll use it instead of git_branch when we need to use it somewhere new - although neither option can guarantee that.

I also like the 7669604 better. It feels cleaner and more self-explanatory, removing the need for the long comment each time the Fastlane helper is called directly.

(Not approving since auto-merge is enabled and I figured I'd let folks with better understanding weigh in here if needed)

[AliSoftware]

I also like the 7669604 better. It feels cleaner and more self-explanatory, removing the need for the long comment each time the Fastlane helper is called directly.

Agreed.

[crazytonyli]

Should current_git_branch be used here too?

[oguzkocer]

🤦 Yes it should be, thank you for catching that!

Addressed in f256ae5.