1.9.0: test_runtime_typing_objects fails #17005

___________________ StubtestUnit.test_runtime_typing_objects ___________________
[gw1] sunos5 -- Python 3.9.18 $(BUILD_DIR)/.tox/py39/bin/python

args = (<mypy.test.teststubtest.StubtestUnit testMethod=test_runtime_typing_objects>,)
kwargs = {}
cases = [<mypy.test.teststubtest.Case object at 0x7fffacfaf550>, <mypy.test.teststubtest.Case object at 0x7fffacfaff10>, <mypy.test.teststubtest.Case object at 0x7fffacfaff40>]
expected_errors = set()
c = <mypy.test.teststubtest.Case object at 0x7fffacfaff40>, @py_assert1 = False
@py_format3 = "{'test_module.Y.__closed__', 'test_module.Y.__extra_items__'} == set()\n~\n~Extra items in the left set:\n~'test_modu...__'\n~\n~Full diff:\n~- set()\n~+ {\n~+     'test_module.Y.__closed__',\n~+     'test_module.Y.__extra_items__',\n~+ }"
@py_format5 = "error: test_module.Y.__closed__ is not present in stub\n~Stub: in file test_module.pyi\n~MISSING\n~Runtime:\n~False\n...__'\n~\n~Full diff:\n~- set()\n~+ {\n~+     'test_module.Y.__closed__',\n~+     'test_module.Y.__extra_items__',\n~+ }"
output = 'error: test_module.Y.__closed__ is not present in stub\nStub: in file test_module.pyi\nMISSING\nRuntime:\nFalse\n\ner... is not present in stub\nStub: in file test_module.pyi\nMISSING\nRuntime:\nNone\n\nFound 2 errors (checked 1 module)\n'
actual_errors = {'test_module.Y.__closed__', 'test_module.Y.__extra_items__'}

    def test(*args: Any, **kwargs: Any) -> None:
        cases = list(fn(*args, **kwargs))
        expected_errors = set()
        for c in cases:
            if c.error is None:
                continue
            expected_error = c.error
            if expected_error == "":
                expected_error = TEST_MODULE_NAME
            elif not expected_error.startswith(f"{TEST_MODULE_NAME}."):
                expected_error = f"{TEST_MODULE_NAME}.{expected_error}"
            assert expected_error not in expected_errors, (
                "collect_cases merges cases into a single stubtest invocation; we already "
                "expect an error for {}".format(expected_error)
            )
            expected_errors.add(expected_error)
        output = run_stubtest(
            stub="\n\n".join(textwrap.dedent(c.stub.lstrip("\n")) for c in cases),
            runtime="\n\n".join(textwrap.dedent(c.runtime.lstrip("\n")) for c in cases),
            options=["--generate-allowlist"],
        )

        actual_errors = set(output.splitlines())
        if actual_errors != expected_errors:
            output = run_stubtest(
                stub="\n\n".join(textwrap.dedent(c.stub.lstrip("\n")) for c in cases),
                runtime="\n\n".join(textwrap.dedent(c.runtime.lstrip("\n")) for c in cases),
                options=[],
            )
>           assert actual_errors == expected_errors, output
E           AssertionError: error: test_module.Y.__closed__ is not present in stub
E             Stub: in file test_module.pyi
E             MISSING
E             Runtime:
E             False
E
E             error: test_module.Y.__extra_items__ is not present in stub
E             Stub: in file test_module.pyi
E             MISSING
E             Runtime:
E             None
E
E             Found 2 errors (checked 1 module)
E
E           assert {'test_module.Y.__closed__', 'test_module.Y.__extra_items__'} == set()
E
E             Extra items in the left set:
E             'test_module.Y.__closed__'
E             'test_module.Y.__extra_items__'
E
E             Full diff:
E             - set()
E             + {
E             +     'test_module.Y.__closed__',
E             +     'test_module.Y.__extra_items__',
E             + }

mypy/test/teststubtest.py:219: AssertionError