Run a deployment when the idempotency key already exists

Help
,
1

I am running a flow from a flow with run_deployment and an idempotency_key. Sometimes, the child flow already exists and I want to do nothing. However in that case, a strange behavior happens:
When looking on the UI to my parent flow, the child flow has not been created but a task appears. This task stay pending forever, even if parent task succeed or fails.
I am wondering if this is a bug or not. Also I am wondering if this task is taking cpu somewhere.

Easy to replicate:
deployer.py

from  prefect.deployments.deployments import Deployment
from flows import child_flow, parent_flow


d1 = Deployment.build_from_flow(
    name='my_parent_deployment',
    flow=parent_flow,
)
d2 = Deployment.build_from_flow(
    name='my_child_deployment',
    flow=child_flow,
)
d1.apply()
d2.apply()

flows.py

from prefect import flow, get_run_logger
from prefect.deployments import run_deployment

@flow
async def parent_flow():
    logger = get_run_logger()
    logger.info("Running parent flow")
    await run_deployment(
        name="child-flow/my_child_deployment",
        idempotency_key="my_idempotency_key",
        timeout=0,
        flow_run_name="child_flow_run",
    )

@flow
async def child_flow():
    logger = get_run_logger()
    logger.info("Running child flow")

And then run the parent deployment twice.

I think the task I see is the one below from prefect.deployments.run_deployment:

        # Generate a task in the parent flow run to represent the result of the subflow
        dummy_task = Task(
            name=deployment_name,
            fn=lambda: None,
            version=deployment.version,
        )

This dummy task is only created when the child deployment is triggered inside a flow as we can see below from prefect.deployments.run_deployment:

    flow_run_ctx = FlowRunContext.get()
        if flow_run_ctx:
               ....

If this behavior is a bug, then we should check that a flow run with the same idempotency_key does not exists before creating the dummy_task.