Notify when product is supplied on sale and has purchase order point
It is often a mistake to set a product as being supplied on sale and with a purchase order point. Even with #11955 which should be used as a transition between the order point to supplied on sale.
So I propose to add a notification warning when user set a product to be supplied on sale if it has already a purchase order point. And also notify the user when he creates an order point for a product which is supplied on sale.