Use git_branch_name_using_HEAD instead of git_branch

CHANGELOG.md

@@ -27,6 +27,7 @@ _None_
 - Replace `rspec-buildkite-analytics` with `buildkite-test_collector` (Buildkite renamed the gem) and update it to `2.2.0`. This is another internal-only change and is not a breaking change for clients. [#465]
 - Adds `ignore_pipeline_branch_filters=true` parameter to the API call triggering a Buildkite build [#468]
 - Replace all instances of `is_string` with `type` [#469]
+- Use `git_branch_name_using_HEAD` instead of `git_branch` so that the return value is not modified by environment variables. This has no impact to our current release flow, that's why it's not in "Breaking changes" section. [#463]
 
 ## 7.0.0
 

lib/fastlane/plugin/wpmreleasetoolkit/actions/android/android_completecodefreeze_prechecks.rb

@@ -6,8 +6,10 @@ def self.run(params)
 
         require_relative '../../helper/android/android_version_helper'
         require_relative '../../helper/android/android_git_helper'
+        require_relative '../../helper/git_helper'
 
-        UI.user_error!("Current branch - '#{other_action.git_branch}' - is not a release branch. Abort.") unless other_action.git_branch.start_with?('release/')
+        current_branch = Fastlane::Helper::GitHelper.current_git_branch
+        UI.user_error!("Current branch - '#{current_branch}' - is not a release branch. Abort.") unless current_branch.start_with?('release/')
 
         version = Fastlane::Helper::Android::VersionHelper.get_public_version
         message = "Completing code freeze for: #{version}\n"

lib/fastlane/plugin/wpmreleasetoolkit/actions/android/android_finalize_prechecks.rb

@@ -10,8 +10,10 @@ def self.run(params)
 
         require_relative '../../helper/android/android_version_helper'
         require_relative '../../helper/android/android_git_helper'
+        require_relative '../../helper/git_helper'
 
-        UI.user_error!('This is not a release branch. Abort.') unless other_action.git_branch.start_with?('release/')
+        current_branch = Fastlane::Helper::GitHelper.current_git_branch
+        UI.user_error!("Current branch - '#{current_branch}' - is not a release branch. Abort.") unless current_branch.start_with?('release/')
 
         version = Fastlane::Helper::Android::VersionHelper.get_public_version
         message = "Finalizing release: #{version}\n"

lib/fastlane/plugin/wpmreleasetoolkit/actions/ios/ios_completecodefreeze_prechecks.rb

@@ -6,8 +6,10 @@ def self.run(params)
 
         require_relative '../../helper/ios/ios_version_helper'
         require_relative '../../helper/ios/ios_git_helper'
+        require_relative '../../helper/git_helper'
 
-        UI.user_error!("Current branch - '#{other_action.git_branch}' - is not a release branch. Abort.") unless other_action.git_branch.start_with?('release/')
+        current_branch = Fastlane::Helper::GitHelper.current_git_branch
+        UI.user_error!("Current branch - '#{current_branch}' - is not a release branch. Abort.") unless current_branch.start_with?('release/')
 
         version = Fastlane::Helper::Ios::VersionHelper.get_public_version
         message = "Completing code freeze for: #{version}\n"

lib/fastlane/plugin/wpmreleasetoolkit/actions/ios/ios_finalize_prechecks.rb

@@ -6,8 +6,10 @@ def self.run(params)
 
         require_relative '../../helper/ios/ios_version_helper'
         require_relative '../../helper/ios/ios_git_helper'
+        require_relative '../../helper/git_helper'
 
-        UI.user_error!('This is not a release branch. Abort.') unless other_action.git_branch.start_with?('release/')
+        current_branch = Fastlane::Helper::GitHelper.current_git_branch
+        UI.user_error!("Current branch - '#{current_branch}' - is not a release branch. Abort.") unless current_branch.start_with?('release/')
 
         version = Fastlane::Helper::Ios::VersionHelper.get_public_version
         message = "Finalizing release: #{version}\n"

lib/fastlane/plugin/wpmreleasetoolkit/helper/git_helper.rb

@@ -181,6 +181,23 @@ def self.fetch_all_tags
         Action.sh('git', 'fetch', '--tags')
       end
 
+      # Returns the current git branch, or "HEAD" if it's not checked out to any branch
+      # Can NOT be replaced using the environment variables such as `GIT_BRANCH` or `BUILDKITE_BRANCH`
+      #
+      # `fastlane` already has a helper action for this called `git_branch`, however it's modified
+      # by CI environment variables. We need to check which branch we are actually on and not the
+      # initial branch a CI build is started from, so we are using the `git_branch_name_using_HEAD`
+      # helper instead.
+      #
+      # See https://docs.fastlane.tools/actions/git_branch/#git_branch
+      #
+      # @return [String] The current git branch, or "HEAD" if it's not checked out to any branch
+      #
+      def self.current_git_branch
+        # We can't use `other_action.git_branch`, because it is modified by environment variables in Buildkite.
+        Fastlane::Actions.git_branch_name_using_HEAD
+      end
+
       # Checks if a branch exists locally.
       #
       # @param [String] branch_name The name of the branch to check for