[FIX] sale_margin: recompute purchase_price on product_id_change.

When creating sale order lines from the matrix (sale_product_matrix),
the purchase_price weren't computed

No cleaner change has been found to ensure the cost is computed.

Triggering all onchanges from the server side is quite tricky and dirty
to do...

closes odoo/odoo#40986

X-original-commit: 5c15b131
Signed-off-by: Victor Feyens (vfe) <vfe@odoo.com>

addons/sale_margin/models/sale_order.py

@@ -40,6 +40,13 @@ class SaleOrderLine(models.Model):
             return
         self.purchase_price = self._compute_margin(self.order_id, self.product_id, self.product_uom)
 
+    @api.onchange('product_id')
+    def product_id_change(self):
+        # VFE FIXME : bugfix for matrix, the purchase_price will be changed to a computed field in master.
+        res = super(SaleOrderLine, self).product_id_change()
+        self.product_id_change_margin()
+        return res
+
     @api.model
     def create(self, vals):
         vals.update(self._prepare_add_missing_fields(vals))