Exposing the GIT_BRANCH ENV variable won't work if user builds specific SHA

[KrauseFx]

I haven't looked into how other CI systems deal with this, but right now we're just falling back to master by default via

ci/app/features/build_runner/remote_runner.rb

Line 251 in 842b999

env_mapping[:GIT_BRANCH] = "master" # TODO: use actual default branch?

This will be interesting when hitting the Rebuild button, where we obviously want to rebuild a specific commit, but also it's usually initially being triggered via branch (e.g. PR). So we want to keep that branch information still.

Relevant PR #1083 cc @AndrewMcBurney

[fastlane-danger-bot]

We decided to pause our work on fastlane.ci to focus on the core fastlane product as we have a lot on the roadmap. You can find more information on the main GitHub page. This issue will be auto-closed 👍