Fixed #24360 -- Delayed internal LocaleMiddleware variable initialization

from django.http import HttpResponseRedirect

from django.utils import translation

from django.utils.cache import patch_vary_headers

from django.utils.functional import cached_property

class LocaleMiddleware(object):

    """

    response_redirect_class = HttpResponseRedirect

    def __init__(self):

        self._is_language_prefix_patterns_used = False

        for url_pattern in get_resolver(None).url_patterns:

            if isinstance(url_pattern, LocaleRegexURLResolver):

                self._is_language_prefix_patterns_used = True

                break

    def process_request(self, request):

        check_path = self.is_language_prefix_patterns_used()

        language = translation.get_language_from_request(

            request, check_path=check_path)

            request, check_path=self.is_language_prefix_patterns_used)

        translation.activate(language)

        request.LANGUAGE_CODE = translation.get_language()

        language = translation.get_language()

        language_from_path = translation.get_language_from_path(request.path_info)

        if (response.status_code == 404 and not language_from_path

                and self.is_language_prefix_patterns_used()):

                and self.is_language_prefix_patterns_used):

            urlconf = getattr(request, 'urlconf', None)

            language_path = '/%s%s' % (language, request.path_info)

            path_valid = is_valid_path(language_path, urlconf)

                )

                return self.response_redirect_class(language_url)

        if not (self.is_language_prefix_patterns_used()

        if not (self.is_language_prefix_patterns_used

                and language_from_path):

            patch_vary_headers(response, ('Accept-Language',))

        if 'Content-Language' not in response:

            response['Content-Language'] = language

        return response

    @cached_property

    def is_language_prefix_patterns_used(self):

        """

        Returns `True` if the `LocaleRegexURLResolver` is used

        at root level of the urlpatterns, else it returns `False`.

        """

        return self._is_language_prefix_patterns_used

        for url_pattern in get_resolver(None).url_patterns:

            if isinstance(url_pattern, LocaleRegexURLResolver):

                return True

        return False