fix a doubtful bug which caused while there's no deffered functions

binded to the blueprint object, and this is the common user case

flask/blueprints.py

@@ -144,6 +144,7 @@ class Blueprint(_PackageBoundObject):
         """
         self._got_registered_once = True
         state = self.make_setup_state(app, options, first_registration)
+        [setattr(self, k, getattr(state, k)) for k in ('subdomain', 'url_prefix', 'url_defaults')]
         if self.has_static_folder:
             state.add_url_rule(self.static_url_path + '/<path:filename>',
                                view_func=self.send_static_file,