```ruby
Spree::Order.class_eval do
  attr_accessible :coupon_code
  attr_accessor :coupon_code

  # Tells us if there if the specified promotion is already associated with the order
  # regardless of whether or not its currently eligible.  Useful because generally
  # you would only want a promotion to apply to order no more than once.
  def promotion_credit_exists?(promotion)
    !! adjustments.promotion.reload.detect { |credit| credit.originator.promotion.id == promotion.id }
  end

  def products
    line_items.map {|li| li.variant.product}
  end

  unless self.method_defined?('update_adjustments_with_promotion_limiting')
    def update_adjustments_with_promotion_limiting
      update_adjustments_without_promotion_limiting
      return if adjustments.promotion.eligible.none?
      most_valuable_adjustment = adjustments.promotion.eligible.max{|a,b| a.amount.abs <=> b.amount.abs}
      current_adjustments = (adjustments.promotion.eligible - [most_valuable_adjustment])
      current_adjustments.each do |adjustment|
        unless adjustment.originator.calculator.is_a?(Spree::Calculator::PerItem)
          adjustment.update_attribute_without_callbacks(:eligible, false)
        end
      end
    end
    alias_method_chain :update_adjustments, :promotion_limiting
  end
end
```

Check for calculator on adjustment.originator in update_adjustments_with_promotion_listing before checking its type
user
```ruby
Spree::Order.class_eval do
  attr_accessible :coupon_code
  attr_accessor :coupon_code

  # Tells us if there if the specified promotion is already associated with the order
  # regardless of whether or not its currently eligible.  Useful because generally
  # you would only want a promotion to apply to order no more than once.
  def promotion_credit_exists?(promotion)
    !! adjustments.promotion.reload.detect { |credit| credit.originator.promotion.id == promotion.id }
  end

  def products
    line_items.map {|li| li.variant.product}
  end

  unless self.method_defined?('update_adjustments_with_promotion_limiting')
    def update_adjustments_with_promotion_limiting
      update_adjustments_without_promotion_limiting
      return if adjustments.promotion.eligible.none?
      most_valuable_adjustment = adjustments.promotion.eligible.max{|a,b| a.amount.abs <=> b.amount.abs}
      current_adjustments = (adjustments.promotion.eligible - [most_valuable_adjustment])
      current_adjustments.each do |adjustment|
        calculator = adjustment.originator.try(:calculator)
        if calculator && !calculator.is_a?(Spree::Calculator::PerItem)
          adjustment.update_attribute_without_callbacks(:eligible, false)
        end
      end
    end
    alias_method_chain :update_adjustments, :promotion_limiting
  end
end
```
assistant