Look like we need to set config.option.threads

Author: DisturbedOcean

tests/conftest.py

@@ -21,6 +21,7 @@ def pytest_configure(config: pytest.Config) -> None:
     Tests must opt-in via @pytest.mark.freethreaded(threads=N, iterations=M).
     """
     if sys.version_info >= (3, 13) and hasattr(config.option, "threads"):
+        config.option.threads = 2
         config.option.iterations = 1