Airflow v2.0b3
 Kubernetes v1.19.3

Discovered issue while testing KubernetesPodOperator (haven't tested with other operator).
If I create a multiline string using """ """", add some variables inside (Jinja templating), then use this string as an argument to KubernetesPodOperator:
- In Graph View DAG is not visible (just gray area where it should be a digraph);
- in browser's web console i see the following error:

`Uncaught TypeError: node is undefined
    preProcessGraph http://localhost:8080/static/dist/dagre-d3.min.js:103
    preProcessGraph http://localhost:8080/static/dist/dagre-d3.min.js:103
    fn http://localhost:8080/static/dist/dagre-d3.min.js:103
    call http://localhost:8080/static/dist/d3.min.js:3
    draw http://localhost:8080/graph?dag_id=mydag&execution_date=mydate
    expand_group http://localhost:8080/graph?dag_id=mydag&execution_date=mydate
    <anonymous> http://localhost:8080/graph?dag_id=mydag&execution_date=mydate`

Tree view works without issues in this case. The DAG succeeds.
airflow/models/baseoperator.py
dags = {
            task._dag.dag_id: task._dag  
            for task in self.roots + task_list
            if task.has_dag()  
        }
        if len(dags) > 1:
            raise AirflowException(
                f'Tried to set relationships between tasks in more than one DAG: {dags.values()}'
            )
        elif len(dags) == 1:
            dag = dags.popitem()[1]
        else:
            raise AirflowException(
                "Tried to create relationships between tasks that don't have "
                "DAGs yet. Set the DAG for at least one "
                "task  and try again: {}".format([self] + task_list)
            )
        if dag and not self.has_dag():
            self.dag = dag
        for task in task_list:
            if dag and not task.has_dag():
                task.dag = dag
            if upstream:
                task.add_only_new(task.get_direct_relative_ids(upstream=False), self.task_id)
                self.add_only_new(self._upstream_task_ids, task.task_id)
            else:
                self.add_only_new(self._downstream_task_ids, task.task_id)
                task.add_only_new(task.get_direct_relative_ids(upstream=True), self.task_id)
    def set_downstream(self, task_or_task_list: Union[TaskMixin, Sequence[TaskMixin]]) -> None: