When using protocol relative URLs, the links in IRC are also protocol relative and not clickable.
See for example #betawiki-rc on Freenode IRC. Example line:
[[MediaWiki:Code-browsing-path/zh-hans]] //translatewiki.net/w/i.php?diff=3182911&oldid=2131330 * Username * (+0)
Relevant code is near line 700 in includes/RecentChange.php: http://svn.wikimedia.org/viewvc/mediawiki/trunk/phase3/includes/RecentChange.php?view=annotate
Version: unspecified
Severity: normal