ayg wrote:

Code posted at [[mw:Help:FAQ]] is not supported, except for modifications to
LocalSettings.php. The breadcrumbs code was added by [[mw:User:Barrylb]], who
is not a developer, and who knows what version he was using, what else he forgot
to add, etc. I suggest you ask him if you have any problems with his code.
Meanwhile, I think I'll be removing that from the FAQ.

http://www.mediawiki.org/w/index.php?title=Help:FAQ&diff=32953&oldid=32949

robchur wrote:

(sigh) Some idiot posted an untested, official hack on our FAQ and made it look
like it had our official support. This is the reason documentation writing
should be made more accountable than the ruddy Wikipedia.

MediaWiki contains limited "breadcrumb" support when using subpages; further
documentation about this SHOULD be available with a little bit of web searching
(though watch out for the false positive of the aforementioned hack) - if not, a
note dropped on one of the help pages on MediaWiki.org will elicit a response.

I've removed the offending misinformation from the FAQ.

robchur wrote:

(In reply to comment #2)

(sigh) Some idiot posted an untested, official hack on our FAQ and made it look

That's "untested, unofficial", even.