As seen on bug 29896 comment 4 about https://arbcom.de.wikipedia.org/ :
Ryan Lane 2011-10-03 13:03:22 PDT
Ugh. Wikis with subdomain names like this are seriously problematic. If you
notice, HTTPS works, but there's a certificate error since it doesn't match
We should actually look at moving sub-subdomains like this to some other name.