`--dist` and `--numprocesses` flags conflict

I would like to use --dist=worksteal with paralellism enabled. I seem to be getting either parallelism or work stealing, but not both together.

I've followed the advice here to print out all of the pytest configuration options:

def test_answer(pytestconfig):
    for item_name in dir(pytestconfig.option):
        if not item_name.startswith("_"):
            print(f"{item_name}: {getattr(pytestconfig.option, item_name)}")
    assert 0  # to see what was printed

--dist=worksteal only:

$ pytest --dist=worksteal test.py | grep "dist:"
dist: worksteal

With parallelism enabled:

$ pytest --numprocesses=auto --dist=worksteal test.py | grep "dist:"
dist: no
$ pytest --dist=worksteal --numprocesses=auto test.py | grep "dist:"
dist: no

Are my expectations wrong? Is there somewhere else I should be looking to check that workstealing is active?

Reproduce the reported commands against test.py, comparing pytest's printed configuration options for --dist=worksteal and --numprocesses=auto. Trace the command-line handling that produces dist: no; done means establishing whether the flags can coexist and either correcting that behavior or documenting the expected configuration.