[FIX] calendar: fix call to get_recurrent_ids broken when migrating

get_recurrent_ids is a multi method. Model should be browsed before calling
the method.

addons/calendar/models/mail_message.py

@@ -26,6 +26,6 @@ class Message(models.Model):
     def _find_allowed_model_wise(self, doc_model, doc_dict):
         if doc_model == 'calendar.event':
             order = self._context.get('order', self._order)
-            for virtual_id in self.env[doc_model].get_recurrent_ids(doc_dict.keys(), [], order=order):
+            for virtual_id in self.env[doc_model].browse(doc_dict.keys()).get_recurrent_ids([], order=order):
                 doc_dict.setdefault(virtual_id, doc_dict[get_real_ids(virtual_id)])
         return super(Message, self)._find_allowed_model_wise(doc_model, doc_dict)