[action] Adds FL_GIT_BRANCH_DONT_USE_ENV_VARS to git_branch (#21597)

fastlane/lib/fastlane/actions/git_branch.rb

@@ -16,7 +16,7 @@ def self.description
       end
 
       def self.details
-        "If no branch could be found, this action will return an empty string. This is a wrapper for the internal action Actions.git_branch"
+        "If no branch could be found, this action will return an empty string. If `FL_GIT_BRANCH_DONT_USE_ENV_VARS` is `true`, it'll ignore CI ENV vars. This is a wrapper for the internal action Actions.git_branch"
       end
 
       def self.available_options

fastlane/lib/fastlane/helper/git_helper.rb

@@ -121,7 +121,10 @@ def self.last_git_commit_hash(short)
 
     # Returns the current git branch, or "HEAD" if it's not checked out to any branch
     # Can be replaced using the environment variable `GIT_BRANCH`
+    # unless `FL_GIT_BRANCH_DONT_USE_ENV_VARS` is `true`
     def self.git_branch
+      return self.git_branch_name_using_HEAD if FastlaneCore::Env.truthy?('FL_GIT_BRANCH_DONT_USE_ENV_VARS')
+
       env_name = SharedValues::GIT_BRANCH_ENV_VARS.find { |env_var| FastlaneCore::Env.truthy?(env_var) }
       ENV.fetch(env_name.to_s) do
         self.git_branch_name_using_HEAD

fastlane/spec/actions_specs/git_branch_spec.rb

@@ -13,6 +13,24 @@
     end
   end
 
+  describe "CI set ENV values but FL_GIT_BRANCH_DONT_USE_ENV_VARS is true" do
+    Fastlane::Actions::SharedValues::GIT_BRANCH_ENV_VARS.each do |env_var|
+      it "gets the value from Git directly with #{env_var}" do
+        expect(Fastlane::Actions).to receive(:sh)
+          .with("git rev-parse --abbrev-ref HEAD", log: false)
+          .and_return("branch-name-from-git")
+
+        FastlaneSpec::Env.with_env_values(env_var => "#{env_var}-branch-name", 'FL_GIT_BRANCH_DONT_USE_ENV_VARS' => 'true') do
+          result = Fastlane::FastFile.new.parse("lane :test do
+            git_branch
+          end").runner.execute(:test)
+
+          expect(result).to eq("branch-name-from-git")
+        end
+      end
+    end
+  end
+
   describe "with no CI set ENV values" do
     it "gets the value from Git directly" do
       expect(Fastlane::Actions).to receive(:sh)