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<a class="wb-external-id" href="https://www.quora.com/topic/Moodle">Moodle</a>
The identifier link with URL formatting is treated like an internal link, which is clearly wrong. The wb-external-id class should style the link as an external link.
Additionally, when $wgNoFollowLinks = true, one would expect all such external links to be nofollow'ed unless whitelisted (e.g. by means of $wgNoFollowDomainExceptions).
If there is a desire to have an on-wiki per-domain whitelisting, similar to the interwiki map, this should be controllable together with the URL formatting (P1630). I'm not sure where the URL-generation code resides though; I think it used to be a gadget.