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.
tests/utils/test_task_group.py
{'id': 'task5'},
        ],
    }
    edges = dag_edges(subdag)
    assert sorted((e["source_id"], e["target_id"]) for e in edges) == [
        ('group234.group34.downstream_join_id', 'task5'),
        ('group234.group34.task3', 'group234.group34.downstream_join_id'),
        ('group234.group34.task4', 'group234.group34.downstream_join_id'),
        ('group234.upstream_join_id', 'group234.group34.task3'),
        ('group234.upstream_join_id', 'group234.group34.task4'),
        ('task1', 'group234.upstream_join_id'),
    ]
    subdag_task_groups = subdag.task_group.get_task_group_dict()
    assert subdag_task_groups.keys() == {None, "group234", "group234.group34"}
    included_group_ids = {"group234", "group234.group34"}
    included_task_ids = {'group234.group34.task3', 'group234.group34.task4', 'task1', 'task5'}
    for task_group in subdag_task_groups.values():
        assert task_group.upstream_group_ids.issubset(included_group_ids)
        assert task_group.downstream_group_ids.issubset(included_group_ids)
        assert task_group.upstream_task_ids.issubset(included_task_ids)
        assert task_group.downstream_task_ids.issubset(included_task_ids)
    for task in subdag.task_group:
        assert task.upstream_task_ids.issubset(included_task_ids)
        assert task.downstream_task_ids.issubset(included_task_ids)
def test_dag_edges():
    execution_date = pendulum.parse("20200101")
    with DAG("test_dag_edges", start_date=execution_date) as dag:
        task1 = DummyOperator(task_id="task1")
        with TaskGroup("group_a") as group_a:
            with TaskGroup("group_b") as group_b: