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
assert extract_node_id(task_group_to_dict(dag.task_group), include_label=True) == {
        'id': None,
        'label': None,
        'children': [
            {
                'id': 'group234',
                'label': 'group234',
                'children': [
                    {
                        'id': 'group34',
                        'label': 'group34',
                        'children': [
                            {
                                'id': 'group34.group4',
                                'label': 'group4',
                                'children': [{'id': 'task4', 'label': 'task4'}],
                            },
                            {'id': 'group34.task3', 'label': 'task3'},
                            {'id': 'group34.downstream_join_id', 'label': ''},
                        ],
                    },
                    {'id': 'task2', 'label': 'task2'},
                    {'id': 'group234.upstream_join_id', 'label': ''},
                ],
            },
            {'id': 'task1', 'label': 'task1'},
            {'id': 'task5', 'label': 'task5'},
        ],
    }
def test_build_task_group_with_task_decorator():