old_contents: default_app_config = 'features.tags.apps.TagsConfig'
  RE_TAG_REF = r'#([a-zA-Z0-9_-]+)'
  
new_contents: default_app_config = 'features.tags.apps.TagsConfig'
  RE_TAG_REF = r'(?:^|\s)#([\w_-]+)'
  
subject: make tags unicode aware and force leading space or beginning of line