They do things like 

    err = PyFile_WriteString("TypeError: print_exception(): Exception expected for value, ", f);
    err += PyFile_WriteString(Py_TYPE(value)->tp_name, f);
    err += PyFile_WriteString(" found\n", f);

which means that PyFile_XXX functions are called after error. They should return (abort printing the exception) instead.


It gets even more interesting with PyFile_WriteObject calls - this function asserts that the exception is not set, so the code calls PyErr_Clear() before calling PyFile_WriteObject(). It should avoid making the call altogether.