Editing number of products in the cart (price issue)

Hi,

There is a problem with editing of a product in the cart by returning to product page:

When I change the number of products and return to the cart, the price of a single product is displayed, no matter how many products I added.

Example:
Product page: add 3 items to cart
Cart: 3 items, 15€ total
Edit by going back to product page, change nr of items to 10
Cart: 10 items, 5€ total

This problem does not appear with in-line editing. Also, when I duplicate within the cart, the price for the duplicated product is updated.

Example (2 steps added to the example above):
Product page: add 3 items to cart
Cart: 3 items, 15€ total
Edit by going back to product page, change nr of items to 10
Cart: 10 items, 5€ total
Duplicate
Cart: 10 items, 5€ total ; 10 items, 50€ total

That is a bug, right?

Best wishes