Notification when trial terminates.

        Trial info is removed from bracket. Triggers halving if bracket is
        not finished.

def on_trial_remove(self, trial_runner, trial):
        """Notification when trial terminates.

        Trial info is removed from bracket. Triggers halving if bracket is
        not finished."""
        bracket, _ = self._trial_info[trial]
        bracket.cleanup_trial(trial)
        if not bracket.finished():
            self._process_bracket(trial_runner, bracket, trial)