Decorate cls.__call__ method to accept old "stop" signature.

def stop_dunder_call_accept_old_params(fn):
    """Decorate cls.__call__ method to accept old "stop" signature."""
    @_utils.wraps(fn)
    def new_fn(self,
               previous_attempt_number=_unset,
               delay_since_first_attempt=_unset,
               retry_state=None):
        if retry_state is None:
            from tenacity import RetryCallState
            retry_state_passed_as_non_kwarg = (
                previous_attempt_number is not _unset and
                isinstance(previous_attempt_number, RetryCallState))
            if retry_state_passed_as_non_kwarg:
                retry_state = previous_attempt_number
            else:
                warn_about_dunder_non_retry_state_deprecation(fn, stacklevel=2)
                retry_state = make_retry_state(
                    previous_attempt_number=previous_attempt_number,
                    delay_since_first_attempt=delay_since_first_attempt)
        return fn(self, retry_state=retry_state)
    return new_fn