code: def fail(value, context_info=None, src_exception=None, err_condition=None):
      
      if isinstance(value, Exception):
          e = as_DAVError(value)
      else:
          e = DAVError(value, context_info, src_exception, err_condition)
      _logger.error("Raising DAVError {}".format(e.get_user_info()))
      raise e
docs: Wrapper to raise (and log) DAVError.