Unable to run container with host's root volume mounted to a container

I am failing to mount the host root within a container when calling DockerClient.containers.run() directly. Here is the failure i hit:

volumes = {"/":{'bind':'/test', 'mode':'rw'}}
client.containers.run(image=<my_image>, volumes=volumes, detach=True, name="voltest1")

docker.errors.APIError: 500 Server Error: Internal Server Error for url: http+docker://localunixsocket/v1.24/containers/create?name=voltest1 ("invalid volume spec "/": invalid volume specification: '/': invalid mount config for type "volume": invalid specification: destination can't be '/'")

If i change the host volume to anything else but root, it works.

Note that I can run this successfully from docker command:
sudo docker run -d -v '/':'/test' --name 'voltest1' <my_image>

Also, I was able to get this to work with the low level API - Create / Start - so not sure why run does not accept this.

Checking the history, looks like the deprecated library had this issue long ago and was fixed:https://github.com/ansible/ansible-modules-core/issues/3823

Has this regressed for the container.run now?

Start with DockerClient.containers.run() and compare how its volume argument is serialized with the low-level Create/Start API and the working docker run command. Reproduce the failure using the shown volumes mapping and verify that mounting host '/' to '/test' succeeds through containers.run() without changing other volume behavior.