[1.8.x] Fixed model_regress test failure on non-ASCII path; refs #24717.

from django.core.files.temp import NamedTemporaryFile

from django.db import DJANGO_VERSION_PICKLE_KEY, models

from django.test import TestCase, mock

from django.utils._os import upath

from django.utils._os import npath, upath

from django.utils.encoding import force_text

from django.utils.version import get_version

            model_regress_path = os.path.abspath(model_regress_dir)

            tests_path = os.path.split(model_regress_path)[0]

            pythonpath = os.environ.get('PYTHONPATH', '')

            pythonpath = os.pathsep.join([tests_path, pythonpath])

            pythonpath = npath(os.pathsep.join([tests_path, pythonpath]))

            with mock.patch.dict('os.environ', {'PYTHONPATH': pythonpath}):

                try: