**Apache Airflow version**:
2.0.1

**Kubernetes version**:
Server Version: version.Info{Major:"1", Minor:"18+", GitVersion:"v1.18.9-eks-d1db3c", GitCommit:"d1db3c46e55f95d6a7d3e5578689371318f95ff9", GitTreeState:"clean", BuildDate:"2020-10-20T22:18:07Z", GoVersion:"go1.13.15", Compiler:"gc", Platform:"linux/amd64"}

**What happened**:
Clearing a failed subdag task with Downstream+Recursive does not automatically set the state of the parent dag to 'running' so that the downstream parent tasks can execute.

The work around is to manually set the state of the parent dag to running after clearing the subdag task

**What you expected to happen**:
With airflow version 1.10.4 the parent dag was automatically set to 'running' for this same scenario

**How to reproduce it**:
- Clear a failed subdag task selecting option for Downstream+Recursive
- See that all down stream tasks in the subdag as well as the parent dag have been cleared
- See that the parent dag is left in 'failed' state. 

tests/models/test_dag.py
@task_decorator
            def return_num(num):
                return num
            return_num(value)
        
        with pytest.raises(TypeError):
            noop_pipeline()  
    def test_dag_param_resolves(self):
        """Test that dag param is correctly resolved by operator"""
        @dag_decorator(default_args=self.DEFAULT_ARGS)
        def xcom_pass_to_op(value=self.VALUE):
            @task_decorator
            def return_num(num):
                return num
            xcom_arg = return_num(value)
            self.operator = xcom_arg.operator  
        dag = xcom_pass_to_op()
        dr = dag.create_dagrun(
            run_id=DagRunType.MANUAL.value,
            start_date=timezone.utcnow(),
            execution_date=self.DEFAULT_DATE,
            state=State.RUNNING,
        )
        self.operator.run(start_date=self.DEFAULT_DATE, end_date=self.DEFAULT_DATE)
        ti = dr.get_task_instances()[0]
        assert ti.xcom_pull() == self.VALUE
    def test_dag_param_dagrun_parameterized(self):
        """Test that dag param is correctly overwritten when set in dag run"""
        @dag_decorator(default_args=self.DEFAULT_ARGS)
        def xcom_pass_to_op(value=self.VALUE):