When I change the quantity of a cart item from the product "configure" page (.../checkout/cart/configure/id/...), the order item quantity is increased with the quantity, instead of updated.
i.e. if I hit the Edit link of a product from my cart, set the quantity to 2 and hit the "Update Cart" button, I end up with a quantity of 3 for this product, instead of 2.
Any helper please ?