[FIX] website_quote: translations for website_description

When creating a SO with a quote template(QT), the website_description
of the QT is transfered with the lang of the partner to the field
website_description of sale.order model(in onchange_template_id on
sale.order model). But when changing the partner_id on the SO, the
lang of the new user was taken into account.

opw:697893

addons/website_quote/models/sale_order.py

@@ -77,6 +77,14 @@ class SaleOrder(models.Model):
             total += line.price_subtotal + line.price_unit * ((line.discount or 0.0) / 100.0) * line.product_uom_qty  # why is there a discount in a field named amount_undiscounted ??
         self.amount_undiscounted = total
 
+    @api.onchange('partner_id')
+    def onchange_update_description_lang(self):
+        if not self.template_id:
+            return
+        else:
+            template = self.template_id.with_context(lang=self.partner_id.lang)
+            self.website_description = template.website_description
+
     @api.onchange('template_id')
     def onchange_template_id(self):
         if not self.template_id: