https://bugzilla.wikimedia.org/show_bug.cgi?id=73184
--- Comment #2 from John Mark Vandenberg jayvdb@gmail.com --- [[s:en:The Army and Navy Hymnal/Catholic/Tantum ergo Sacramentum]] is an interlang redirects.
And this is why interwikis are, by policy but not software, not allowed in redirects, and should be replaced with {{soft redirect}}. The mediawiki bug for this is bug 39492.
I've lower the priority because the script skips this page, and should skip this page - the output is wrong.
This problem dates back to the original 'core' function getredirtarget, line 547-8
http://git.wikimedia.org/blobdiff/pywikibot%2Fcore.git/852973b62c9d597db5fb0...
if "pages" not in result['query']: # no "pages" element indicates a circular redirect raise pywikibot.CircularRedirect....
The result doesnt have pages, because en.ws cant return content that is on another wiki - la.ws.
{"query":{"redirects":[{"from":"The Army and Navy Hymnal/Catholic/Tantum ergo Sacramentum","to":"la:The Army and Navy Hymnal/Catholic/Tantum Ergo"}],"userinfo":{"id":10823,"name":"JVbot"}}}
There is a chance that other text in a #redirect might also cause the same error, but I doubt it.