[FIX] purchase: no unit price and tax update

If no seller is found, do not update unit price and taxes. Indeed, if the
user changes the quantity, it will reset the unit price and the taxes,
which is confusing.

opw-653094

addons/purchase/purchase.py

@@ -562,6 +562,14 @@ class PurchaseOrderLine(models.Model):
             self.product_uom = self.product_id.uom_po_id
         result['domain'] = {'product_uom': [('category_id', '=', self.product_id.uom_id.category_id.id)]}
 
+        product_lang = self.product_id.with_context({
+            'lang': self.partner_id.lang,
+            'partner_id': self.partner_id.id,
+        })
+        self.name = product_lang.display_name
+        if product_lang.description_purchase:
+            self.name += '\n' + product_lang.description_purchase
+
         seller = self.product_id._select_seller(
             self.product_id,
             partner_id=self.partner_id,
@@ -569,6 +577,12 @@ class PurchaseOrderLine(models.Model):
             date=self.order_id.date_order and self.order_id.date_order[:10],
             uom_id=self.product_uom)
 
+        if seller or not self.date_planned:
+            self.date_planned = self._get_date_planned(seller).strftime(DEFAULT_SERVER_DATETIME_FORMAT)
+
+        if not seller:
+            return result
+
         fpos = self.order_id.fiscal_position_id
         self.taxes_id = fpos.map_tax(self.product_id.supplier_taxes_id)
 
@@ -576,16 +590,7 @@ class PurchaseOrderLine(models.Model):
         if price_unit and seller and self.order_id.currency_id and seller.currency_id != self.order_id.currency_id:
             price_unit = seller.currency_id.compute(price_unit, self.order_id.currency_id)
         self.price_unit = price_unit
-        if seller or not self.date_planned:
-            self.date_planned = self._get_date_planned(seller).strftime(DEFAULT_SERVER_DATETIME_FORMAT)
 
-        product_lang = self.product_id.with_context({
-            'lang': self.partner_id.lang,
-            'partner_id': self.partner_id.id,
-        })
-        self.name = product_lang.display_name
-        if product_lang.description_purchase:
-            self.name += '\n' + product_lang.description_purchase
 
 
 class ProcurementRule(models.Model):