Adding a product with a max quantity less than quantity results in max_quantity==quantity

app/models/spree/order_decorator.rb

@@ -18,6 +18,10 @@ Spree::Order.class_eval do
   def set_variant_attributes(variant, attributes)
     line_item = contains?(variant)
 
+    if attributes.key?(:max_quantity) && attributes[:max_quantity].to_i < line_item.quantity
+      attributes[:max_quantity] = line_item.quantity
+    end
+
     line_item.assign_attributes(attributes)
     line_item.save!
   end

spec/requests/consumer/add_to_cart_spec.rb

@@ -136,5 +136,23 @@ feature %q{
     page.should_not have_selector "#variant_attributes_#{p.master.id}_max_quantity"
   end
 
+  scenario "adding a product with a max quantity less than quantity results in max_quantity==quantity" do
+    # Given a group buy product and a distributor
+    d = create(:distributor)
+    p = create(:product, :distributors => [d], :group_buy => true)
+
+    # When I add the item to my cart
+    visit spree.product_path p
+    fill_in "variants_#{p.master.id}", :with => 2
+    fill_in "variant_attributes_#{p.master.id}_max_quantity", :with => 1
+    click_button 'Add To Cart'
+
+    # Then the item should be in my cart with correct quantities
+    order = Spree::Order.last
+    li = order.line_items.first
+    li.product.should == p
+    li.quantity.should == 2
+    li.max_quantity.should == 2
+  end
 
 end