How to config token_pattern for CountVectorsFeaturizer in config.yml?

In the config.yml I want to config token_pattern: r’(?u)\b\w+\b’ for chinese under CountVectorsFeaturizer Component. But it doesn’t work.

# Configuration for Rasa NLU.
language: "zh"
- name: "JiebaTokenizer"
  dictionary_path: "jieba_dict"
- name: "RegexFeaturizer"
- name: "CRFEntityExtractor"
- name: "EntitySynonymMapper"
- name: "CountVectorsFeaturizer"
  token_pattern: r'(?u)\b\w+\b'
- name: "EmbeddingIntentClassifier"

# Configuration for Rasa Core.
  - name: MemoizationPolicy
  - name: KerasPolicy
  - name: MappingPolicy
  - name: "FallbackPolicy"
    nlu_threshold: 0.3
    core_threshold: 0.3
    fallback_action_name: 'action_default_fallback'

CountVectorsFeaturizer reads my configuration r’(?u)\b\w+\b’ as a normal string not a regex. and failed in train method and go into exception brach:

            # noinspection PyPep8Naming
            X = self.vectorizer.fit_transform(lem_exs).toarray()
        except ValueError:
            self.vectorizer = None (will come here)