Test failure with Python 3.14 alpha 2

[frenzymadness]

When testing cloudpickle with Python 3.14 alpha 2, it fails with the following error:

_____________________ CloudPickleFileTests.test_empty_file _____________________
self = <cloudpickle.cloudpickle.Pickler object at 0x7f5616c94220>
obj = <_io.TextIOWrapper name='/tmp/tmpfi2sfxwg/testfile' mode='r' encoding='UTF-8'>
    def dump(self, obj):
        try:
>           return super().dump(obj)
cloudpickle/cloudpickle.py:1295: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
cloudpickle/cloudpickle.py:1380: in reducer_override
    return self._function_reduce(obj)
cloudpickle/cloudpickle.py:1258: in _function_reduce
    return self._dynamic_function_reduce(obj)
cloudpickle/cloudpickle.py:1243: in _dynamic_function_reduce
    state = _function_getstate(func)
cloudpickle/cloudpickle.py:719: in _function_getstate
    f_globals_ref = _extract_code_globals(func.__code__)
cloudpickle/cloudpickle.py:307: in _extract_code_globals
    out_names = _extract_code_globals_cache.get(co)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
self = <WeakKeyDictionary at 0x7f56178d3a80>
key = <code object _make_function at 0x7f5617715e90, file "/builddir/build/BUILD/python-cloudpickle-3.1.0-build/cloudpickle-3.1.0/cloudpickle/cloudpickle.py", line 505>
default = None
    def get(self, key, default=None):
>       return self.data.get(ref(key),default)
E       RecursionError: maximum recursion depth exceeded in comparison
E       when serializing function reconstructor
E       when serializing function object
E       when serializing function reconstructor
E       when serializing function object
E       when serializing function reconstructor
E       when serializing function object
…

[vstinner]

It reported the issue to Python upstream: python/cpython#127597 It's not a Python regression.

[vstinner]

I proposed #545 to port cloudpickle to Python 3.14.