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
if isinstance(arg, XComArg):
                self.set_upstream(arg.operator)
            elif isinstance(arg, (tuple, set, list)):
                for elem in arg:
                    apply_set_upstream(elem)
            elif isinstance(arg, dict):
                for elem in arg.values():
                    apply_set_upstream(elem)
            elif hasattr(arg, "template_fields"):
                for elem in arg.template_fields:
                    apply_set_upstream(elem)
        for field in self.template_fields:
            if hasattr(self, field):
                arg = getattr(self, field)
                apply_set_upstream(arg)
    @property
    def priority_weight_total(self) -> int:
        """
        Total priority weight for the task. It might include all upstream or downstream tasks.
        depending on the weight rule.
          - WeightRule.ABSOLUTE - only own weight
          - WeightRule.DOWNSTREAM - adds priority weight of all downstream tasks
          - WeightRule.UPSTREAM - adds priority weight of all upstream tasks
        """
        if self.weight_rule == WeightRule.ABSOLUTE:
            return self.priority_weight
        elif self.weight_rule == WeightRule.DOWNSTREAM:
            upstream = False
        elif self.weight_rule == WeightRule.UPSTREAM: