Don't extend domain but wrap into a new list

review1106002
(transplanted from e4a2d43ad02e5c5d3ddd4c22a3c2a0890afff0aa)

tryton/gui/window/view_form/view/form_gtk/one2many.py

@@ -370,8 +370,7 @@ class One2Many(WidgetInterface):
         self.view.set_value()
         domain = self.field.domain_get(self.record)
         context = self.field.context_get(self.record)
-        domain = domain[:]
-        domain.extend(self.record.expr_eval(self.attrs.get('add_remove')))
+        domain = [domain, self.record.expr_eval(self.attrs.get('add_remove'))]
         removed_ids = self.field.get_removed_ids(self.record)
 
         self.focus_out = False