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
if end_date:
            self.end_date = timezone.convert_to_utc(end_date)
        if not TriggerRule.is_valid(trigger_rule):
            raise AirflowException(
                "The trigger_rule must be one of {all_triggers},"
                "'{d}.{t}'; received '{tr}'.".format(
                    all_triggers=TriggerRule.all_triggers(),
                    d=dag.dag_id if dag else "",
                    t=task_id,
                    tr=trigger_rule,
                )
            )
        self.trigger_rule = trigger_rule
        self.depends_on_past = depends_on_past
        self.wait_for_downstream = wait_for_downstream
        if wait_for_downstream:
            self.depends_on_past = True
        self.retries = retries
        self.queue = queue
        self.pool = Pool.DEFAULT_POOL_NAME if pool is None else pool
        self.pool_slots = pool_slots
        if self.pool_slots < 1:
            raise AirflowException(f"pool slots for {self.task_id} in dag {dag.dag_id} cannot be less than 1")
        self.sla = sla
        self.execution_timeout = execution_timeout
        self.on_execute_callback = on_execute_callback
        self.on_failure_callback = on_failure_callback
        self.on_success_callback = on_success_callback
        self.on_retry_callback = on_retry_callback
        if isinstance(retry_delay, timedelta):