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
"""
        Lock task for execution to disable custom action in __setattr__ and
        returns a copy of the task
        """
        other = copy.copy(self)
        other._lock_for_execution = True  
        return other
    def set_xcomargs_dependencies(self) -> None:
        """
        Resolves upstream dependencies of a task. In this way passing an ``XComArg``
        as value for a template field will result in creating upstream relation between
        two tasks.
        **Example**: ::
            with DAG(...):
                generate_content = GenerateContentOperator(task_id="generate_content")
                send_email = EmailOperator(..., html_content=generate_content.output)
            # This is equivalent to
            with DAG(...):
                generate_content = GenerateContentOperator(task_id="generate_content")
                send_email = EmailOperator(
                    ..., html_content="{{ task_instance.xcom_pull('generate_content') }}"
                )
                generate_content >> send_email
        """
        from airflow.models.xcom_arg import XComArg
        def apply_set_upstream(arg: Any):