rollback! (Capistrano::Configuration::Execution)

    # File lib/capistrano/configuration/execution.rb, line 109
          def rollback!
            return if Thread.current[:rollback_requests].nil?
            Thread.current[:rolled_back] = true

            # throw the task back on the stack so that roles are properly
            # interpreted in the scope of the task in question.
            rollback_requests.reverse.each do |frame|
              begin
                push_task_call_frame(frame.task)
                logger.important "rolling back", frame.task.fully_qualified_name
                frame.rollback.call
              rescue Object => e
                logger.info "exception while rolling back: #{e.class}, #{e.message}", frame.task.fully_qualified_name
              ensure
                pop_task_call_frame
              end
            end
          end