[FIX] sale_mrp: COGS in case of kit

When a kit is sold, the unit price of the COGS recorded is the sum of
the unit prices of each component multiplies by the quantity sold.
Obviously, this is not correct since the unit price should not take into
account the quantity sold.

opw-681403

addons/sale_mrp/sale_mrp.py

@@ -141,7 +141,7 @@ class AccountInvoiceLine(models.Model):
                         prod_moves = [m for m in moves if m.product_id.id == product_id]
                         prod_qty_done = factor * qty_done
                         prod_quantity = factor * quantity
-                        average_price_unit += factor * self._compute_average_price(prod_qty_done, prod_quantity, prod_moves)
+                        average_price_unit += self._compute_average_price(prod_qty_done, prod_quantity, prod_moves)
                     price_unit = average_price_unit or price_unit
                     price_unit = uom_obj._compute_qty_obj(self.uom_id, price_unit, self.product_id.uom_id, round=False)
         return price_unit