Notification to TrialScheduler and requeue trial.

        This does not notify the SearchAlgorithm because the function
        evaluation is still in progress.

def _requeue_trial(self, trial):
        """Notification to TrialScheduler and requeue trial.

        This does not notify the SearchAlgorithm because the function
        evaluation is still in progress.
        """
        self._scheduler_alg.on_trial_error(self, trial)
        self.trial_executor.set_status(trial, Trial.PENDING)
        with warn_if_slow("scheduler.on_trial_add"):
            self._scheduler_alg.on_trial_add(self, trial)