**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. 

airflow/models/dag.py
creating_job_id: Optional[int] = None,
    ):
        """
        Creates a dag run from this dag including the tasks associated with this dag.
        Returns the dag run.
        :param run_id: defines the run id for this dag run
        :type run_id: str
        :param run_type: type of DagRun
        :type run_type: airflow.utils.types.DagRunType
        :param execution_date: the execution date of this dag run
        :type execution_date: datetime.datetime
        :param state: the state of the dag run
        :type state: airflow.utils.state.State
        :param start_date: the date this dag run should be evaluated
        :type start_date: datetime
        :param external_trigger: whether this dag run is externally triggered
        :type external_trigger: bool
        :param conf: Dict containing configuration/parameters to pass to the DAG
        :type conf: dict
        :param creating_job_id: id of the job creating this DagRun
        :type creating_job_id: int
        :param session: database session
        :type session: sqlalchemy.orm.session.Session
        :param dag_hash: Hash of Serialized DAG
        :type dag_hash: str
        """
        if run_id and not run_type:
            if not isinstance(run_id, str):
                raise ValueError(f"`run_id` expected to be a str is {type(run_id)}")
            run_type: DagRunType = DagRunType.from_run_id(run_id)