Fixed #19485 -- Python 3 compatibility for c2a6b2a4.

def code_changed():

    global _mtimes, _win

    filenames = [getattr(m, "__file__", None) for m in sys.modules.values()]

    for filename in filter(None, filenames) + _error_files:

    filenames = []

    for m in sys.modules.values():

        try:

            filenames.append(m.__file__)

        except AttributeError:

            pass

    for filename in filenames + _error_files:

        if filename.endswith(".pyc") or filename.endswith(".pyo"):

            filename = filename[:-1]

        if filename.endswith("$py.class"):