merge_multi_values

# File activerecord/lib/active_record/relation/merger.rb, line 131
      def merge_multi_values
        if other.reordering_value
          # override any order specified in the original relation
          relation.reorder! other.order_values
        elsif other.order_values
          # merge in order_values from relation
          relation.order! other.order_values
        end

        relation.extend(*other.extending_values) unless other.extending_values.blank?
      end