Pauses the trial.

        If trial is in-flight, preserves return value in separate queue
        before pausing, which is restored when Trial is resumed.

def pause_trial(self, trial):
        """Pauses the trial.

        If trial is in-flight, preserves return value in separate queue
        before pausing, which is restored when Trial is resumed.
        """

        trial_future = self._find_item(self._running, trial)
        if trial_future:
            self._paused[trial_future[0]] = trial
        super(RayTrialExecutor, self).pause_trial(trial)