Does the PySequence_Fast result need releasing if the following “for” loop fails? There is a Py_DECREF only in the successful case, which seems inconsistent.

Does Python still support non-UTF-8 locales and bytes filenames? I haven’t been keeping up, but I assumed these things were still supported in many cases. It seems strange to only support UTF-8 in the “addopen” file action.

Pablo’s second PR currently <https://github.com/python/cpython/pull/5418/commits/e50bdb9> calls PyErr_SetString(PyExc_OSError, . . .) with a custom error message depending on which OS call failed. But I wonder if it is more important to set the “errno” attribute (which I think should choose an OSError subclass if appropriate). Perhaps you can do that by assigning the return values to “errno” and then calling PyErr_SetFromErrno. A disadvantage might be less context about which stage went wrong.