⚠️ CI failed on Linux_Nightly.pylatest_pip_scipy_dev (last failure: Oct 17, 2025) ⚠️

**CI is still failing on [Linux_Nightly.pylatest_pip_scipy_dev](https://dev.azure.com/scikit-learn/scikit-learn/_build/results?buildId=81313&view=logs&j=dfe99b15-50db-5d7b-b1e9-4105c42527cf)** (Oct 17, 2025)
- test_pandas_arff_parser_strip_single_quotes[_liac_arff_parser]
- test_pandas_arff_parser_strip_double_quotes[_liac_arff_parser]
- test_fetch_openml_as_frame_true[True-liac-arff-61-dataset_params0-150-4-1]
- test_fetch_openml_as_frame_true[True-liac-arff-61-dataset_params1-150-4-1]
- test_fetch_openml_as_frame_true[True-liac-arff-2-dataset_params2-11-38-1]
- test_fetch_openml_as_frame_true[True-liac-arff-2-dataset_params3-11-38-1]
- test_fetch_openml_as_frame_true[True-liac-arff-561-dataset_params4-209-7-1]
- test_fetch_openml_as_frame_true[True-liac-arff-561-dataset_params5-209-7-1]
- test_fetch_openml_as_frame_true[True-liac-arff-40589-dataset_params6-13-72-6]
- test_fetch_openml_as_frame_true[True-liac-arff-1119-dataset_params7-10-14-1]
- test_fetch_openml_as_frame_true[True-liac-arff-1119-dataset_params8-10-14-1]
- test_fetch_openml_as_frame_true[True-liac-arff-40966-dataset_params9-7-77-1]
- test_fetch_openml_as_frame_true[True-liac-arff-40966-dataset_params10-7-77-1]
- test_fetch_openml_as_frame_true[True-liac-arff-40945-dataset_params11-1309-13-1]
- test_fetch_openml_as_frame_true[False-liac-arff-61-dataset_params0-150-4-1]
- test_fetch_openml_as_frame_true[False-liac-arff-61-dataset_params1-150-4-1]
- test_fetch_openml_as_frame_true[False-liac-arff-2-dataset_params2-11-38-1]
- test_fetch_openml_as_frame_true[False-liac-arff-2-dataset_params3-11-38-1]
- test_fetch_openml_as_frame_true[False-liac-arff-561-dataset_params4-209-7-1]
- test_fetch_openml_as_frame_true[False-liac-arff-561-dataset_params5-209-7-1]
- test_fetch_openml_as_frame_true[False-liac-arff-40589-dataset_params6-13-72-6]
- test_fetch_openml_as_frame_true[False-liac-arff-1119-dataset_params7-10-14-1]
- test_fetch_openml_as_frame_true[False-liac-arff-1119-dataset_params8-10-14-1]
- test_fetch_openml_as_frame_true[False-liac-arff-40966-dataset_params9-7-77-1]
- test_fetch_openml_as_frame_true[False-liac-arff-40966-dataset_params10-7-77-1]
- test_fetch_openml_as_frame_true[False-liac-arff-40945-dataset_params11-1309-13-1]
- test_fetch_openml_consistency_parser[61]
- test_fetch_openml_consistency_parser[1119]
- test_fetch_openml_consistency_parser[40945]
- test_fetch_openml_equivalence_array_dataframe[liac-arff]
- test_fetch_openml_iris_pandas[liac-arff]
- test_fetch_openml_forcing_targets[petalwidth-liac-arff]
- test_fetch_openml_forcing_targets[target_column1-liac-arff]
- test_fetch_openml_equivalence_frame_return_X_y[liac-arff-61]
- test_fetch_openml_equivalence_frame_return_X_y[liac-arff-2]
- test_fetch_openml_equivalence_frame_return_X_y[liac-arff-561]
- test_fetch_openml_equivalence_frame_return_X_y[liac-arff-40589]
- test_fetch_openml_equivalence_frame_return_X_y[liac-arff-1119]
- test_fetch_openml_types_inference[True-61-liac-arff-1-4-0]
- test_fetch_openml_types_inference[True-2-liac-arff-33-6-0]
- test_fetch_openml_types_inference[True-561-liac-arff-1-7-0]
- test_fetch_openml_types_inference[True-40589-liac-arff-6-72-0]
- test_fetch_openml_types_inference[True-1119-liac-arff-9-6-0]
- test_fetch_openml_types_inference[True-40966-liac-arff-1-77-0]
- test_fetch_openml_types_inference[True-40945-liac-arff-3-6-0]
- test_fetch_openml_types_inference[False-61-liac-arff-1-4-0]
- test_fetch_openml_types_inference[False-2-liac-arff-33-6-0]
- test_fetch_openml_types_inference[False-561-liac-arff-1-7-0]
- test_fetch_openml_types_inference[False-40589-liac-arff-6-72-0]
- test_fetch_openml_types_inference[False-1119-liac-arff-9-6-0]
- test_fetch_openml_types_inference[False-40966-liac-arff-1-77-0]
- test_fetch_openml_types_inference[False-40945-liac-arff-3-6-0]
- test_convert_arff_data_dataframe_warning_low_memory_pandas
- test_missing_values_pandas[liac-arff-True]
- test_missing_values_pandas[liac-arff-False]
- test_fetch_openml_strip_quotes
- test_fetch_openml_leading_whitespace
- test_fetch_openml_quotechar_escapechar

COMMENT:
<del>I seems we have discovered a bug in CPython 3.14's contextlib... I will try to craft a minimal reproducer independently of scikit-learn/openml and then investigate the cause in our code.</del>

I misread the traceback, it's a problem in pandas:

```python
        if len(args) == 1 and isinstance(args[0], dict):
            args = tuple(kv for item in args[0].items() for kv in item)
    
        if len(args) % 2 != 0 or len(args) < 2:
            raise ValueError(
                "Provide an even amount of arguments as "
                "option_context(pat, val, pat, val...)."
            )
    
        ops = tuple(zip(args[::2], args[1::2], strict=True))
        try:
            undo = tuple((pat, get_option(pat)) for pat, val in ops)
            for pat, val in ops:
                set_option(pat, val)
            yield
        finally:
>           for pat, val in undo:
                            ^^^^
E           UnboundLocalError: cannot access local variable 'undo' where it is not associated with a value

args       = ('future.no_silent_downcasting', True)
ops        = (('future.no_silent_downcasting', True),)

../../miniforge3/envs/testvenv/lib/python3.14/site-packages/pandas/_config/config.py:512: UnboundLocalError

```

Labels: Bug