test_list.ListTest.test_no_memory fails under tracerefs

[mpage]

Bug report

Bug description:

After gh-130811, test_list.ListTest.test_no_memory fails when CPython is configured with --with-trace-refs, because memory allocation fails in _PyRefchain_Trace and an unexpected error is produced:

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FAIL: test_no_memory (test.test_list.ListTest.test_no_memory)
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Traceback (most recent call last):
  File "/home/encukou/dev/cpython/Lib/test/test_list.py", line 328, in test_no_memory
    self.assertIn("MemoryError", err.decode("utf-8"))
    ~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError: 'MemoryError' not found in 'Fatal Python error: _PyRefchain_Trace: _Py_hashtable_set() memory allocation failed\nPython runtime state: initialized\n\nCurrent thread 0x00007ff7cc547740 (most recent call first):\n  File "<string>", line 7 in <module>\n\nExtension modules: _testcapi (total: 1)\n'

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CPython versions tested on:

CPython main branch

Operating systems tested on:

Linux

[mpage]

Fixed by gh-130921