The initializer looks like this:

      def initialize(configuration, root = Rails.root)
        @configuration, @root = configuration, root
      end

And DatabaseTasks.create can pass mutiple arguments:

      def create(*arguments)
        configuration = arguments.first
        class_for_adapter(configuration['adapter']).new(*arguments).create

Though in all places I managed to find the create method is called only with one argument. So I guess that yes, it's safe to join on root directly. I'll make a fix soon.