i18n redirect_on_fallback=False and public=False bug

[stefanfoulis]

the combination of redirect_on_fallback=False with public=False creates undesired results.

LANGUAGE_CODE='de'
CMS_LANGUAGES = {
    1: [
        {
            'code': 'de',
            'name': _('German'),
        },
        {
            'code': 'en',
            'name': _('English'),
            'public': False,
        },
    ],
    'default': {
        'fallbacks': ['en', 'de'],
        'redirect_on_fallback': True,
        'hide_untranslated': False,
        'public': True,
    }
}

With the above settings, if you have a navigate to /en/ (or have language cookie set to 'en' or your default browser language is 'en') as an anonymous/non-staff user, you'll see a page without content.

Expected would be either a redirect to the default language or a 404 (redirect would be more practical).