merge_multi_values

# File activerecord/lib/active_record/relation/merger.rb, line 132
      def merge_multi_values
        lhs_wheres = relation.where_values
        rhs_wheres = other.where_values

        lhs_binds  = relation.bind_values
        rhs_binds  = other.bind_values

        removed, kept = partition_overwrites(lhs_wheres, rhs_wheres)

        where_values = kept + rhs_wheres
        bind_values  = filter_binds(lhs_binds, removed) + rhs_binds

        relation.where_values = where_values
        relation.bind_values  = bind_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