I encounter the same failure when running test_posix suite with a debug build Python.
[root@SZX1000328166 cpython]# ./python -m test test_posix
Run tests sequentially
0:00:00 load avg: 0.91 [1/1] test_posix
Warning -- files was modified by test_posix
Before: []
After: ['\udcdb\udcdb\udcdb\udcdb\udcdb\udcdb\udcdb\udcdb\udcdb\udcdb\udcdb\udcdb\udcdb\udcdb\udcdb\udcdb\udcdb\udcdb\udcdb\udcdb\udcdb\udcdb\udcdb\udcdb\udcdb\udcdb\udcdb\udcdb\udcdb\udcdb\udcdb\udcdb\udcf0\udcd3B\udcb4\udc8b\x7f']
test test_posix failed -- multiple errors occurred; run in verbose mode for details
test_posix failed
== Tests result: FAILURE ==
1 test failed:
test_posix
Total duration: 459 ms
Tests result: FAILURE
Believe it or not, when I comment out the `Py_DECREF(path)`, the failure goes away.