[FIX] purchase: kit and unit price

When buying a kit, the components should not get their unit price on the
kit. By doing this patch + a previous that set the unit_price on the
move as copy False, it'll take the standard price.

addons/purchase/models/stock.py

@@ -48,7 +48,7 @@ class StockMove(models.Model):
     def _get_price_unit(self):
         """ Returns the unit price for the move"""
         self.ensure_one()
-        if self.purchase_line_id:
+        if self.purchase_line_id and self.product_id.id == self.purchase_line_id.product_id.id:
             line = self.purchase_line_id
             order = line.order_id
             price_unit = line.price_unit