Wikimedia Bugzilla is closed!

As Dantman points out, "Interwiki patterns also do not support generic URLs very well. They are primarily intended for other wikis and hence MediaWiki currently does some encoding of the value after the prefix: in ways that make it unusable for adding new sites generically, for example see what it does to a google: interwiki link." This would present a barrier to using the interwiki table as a spam whitelist for those URLs. https://www.mediawiki.org/wiki/Alternatives_to_applying_the_same_nofollow/dofollow_value_to_all_external_links#Make_more_use_of_interwiki_links

We could add a serialized field to the interwiki table that uses regular expressions to change, say, spaces to plus signs, if that's how the website formats its URLs. I'm not all that skilled with regular expressions, and my use cases are usually pretty simple, so I just use https://www.mediawiki.org/wiki/Extension:InterwikiRegex , which uses str_replace. Regex would be more powerful, though.