ayg wrote:

See also bug 4899 and dependencies. This looks like yet another consequence of logic duplication between Parser and other stuff. However, I can't reproduce with the provided code (see URL).

circeus wrote:

Maybe it has to do with the version of MediaWiki Wikipedia uses? And is it possible the section 0 edit link script interferes?

ayg wrote:

All Wikimedia installations are using the same version of the software. If you think JavaScript may be an issue (unlikely), please turn off JavaScript to test and then report back. Try to make a page wherever you like exhibiting the problem and link to it from here. We can't do very much if we can't see the bug occurring.

EN.WP.ST47 wrote:

Here is an example revid of this bug from Wikipedia:
http://en.wikipedia.org/w/index.php?title=Wikipedia:Sandbox&oldid=417997227

Present in 1.16.2 release as well:
Installed software

Product Version
MediaWiki 1.16.2
PHP 5.2.0-8+etch16 (cgi-fcgi)
MySQL 5.0.51a-24+lenny2+spu1
Installed extensions

Extension functions
wfwebsiteFrame
Parser extension tags
<gallery>, <nowiki>, <pre> and <websiteframe>
Parser function hooks
anchorencode, basepagename, basepagenamee, defaultsort, displaytitle, filepath, formatdate, formatnum, fullpagename, fullpagenamee, fullurl, fullurle, gender, grammar, int, language, lc, lcfirst, localurl, localurle, namespace, namespacee, ns, nse, numberingroup, numberofactiveusers, numberofadmins, numberofarticles, numberofedits, numberoffiles, numberofpages, numberofusers, numberofviews, padleft, padright, pagename, pagenamee, pagesincategory, pagesize, plural, protectionlevel, special, subjectpagename, subjectpagenamee, subjectspace, subjectspacee, subpagename, subpagenamee, tag, talkpagename, talkpagenamee, talkspace, talkspacee, uc, ucfirst and urlencode