https://bugzilla.wikimedia.org/show_bug.cgi?id=73184
--- Comment #4 from John Mark Vandenberg jayvdb@gmail.com --- @Mpaa, well mediawiki has limited support for interwiki links in redirects. It may even be a LocalSettings.php config variable to make interwiki links not automatically redirect.
Pywikibot needs to detect them, and .. either access them normally or raise an appropriate exception. InterwikiRedirectPage subclass of PageRelatedError.
I'd prefer that we consider it an invalid page and raise an exception, because I expect there is a lot of code which believes that a redirect target will always be on the same site as the redirect. The API cant 'follow redirects' if the redirect is an interwiki link.