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
"""
        Called for [Operator] > [Outlet], so that if other is an attr annotated object
        it is set as an outlet of this Operator.
        """
        if not isinstance(other, Iterable):
            other = [other]
        for obj in other:
            if not attr.has(obj):
                raise TypeError(f"Left hand side ({obj}) is not an outlet")
        self.add_outlets(other)
        return self
    def __lt__(self, other):
        """
        Called for [Inlet] > [Operator] or [Operator] < [Inlet], so that if other is
        an attr annotated object it is set as an inlet to this operator
        """
        if not isinstance(other, Iterable):
            other = [other]
        for obj in other:
            if not attr.has(obj):
                raise TypeError(f"{obj} cannot be an inlet")
        self.add_inlets(other)
        return self
    def __setattr__(self, key, value):