Fix wrong behavior in case of bulk rejection

IPython/utils/traitlets.py

@@ -624,6 +624,7 b' class HasTraits(py3compat.with_metaclass(MetaHasTraits, object)):'
                             setattr(self, name, cache[name][1])
                         else:
                             delattr(self, name)
+                    cache = {}
                     notifications = {}
                     raise e
                 finally: