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
self.__dict__ = state  
        self._log = logging.getLogger("airflow.task.operators")
    def render_template_fields(self, context: Dict, jinja_env: Optional[jinja2.Environment] = None) -> None:
        """
        Template all attributes listed in template_fields. Note this operation is irreversible.
        :param context: Dict with values to apply on content
        :type context: dict
        :param jinja_env: Jinja environment
        :type jinja_env: jinja2.Environment
        """
        if not jinja_env:
            jinja_env = self.get_template_env()
        self._do_render_template_fields(self, self.template_fields, context, jinja_env, set())
    def _do_render_template_fields(
        self,
        parent: Any,
        template_fields: Iterable[str],
        context: Dict,
        jinja_env: jinja2.Environment,
        seen_oids: Set,
    ) -> None:
        for attr_name in template_fields:
            content = getattr(parent, attr_name)
            if content:
                rendered_content = self.render_template(content, context, jinja_env, seen_oids)
                setattr(parent, attr_name, rendered_content)
    def render_template(