Pre-XHTML HTML allows a number of elements to be implicitly closed,
such as <li> within a <ul> or <ol>.
In 1.5, MediaWiki allowed this code through:
While invalid XHTML due to not being well-formed, this did render
in browsers the way people would expect from traditional HTML.
In 1.6 and current trunk, this is smashed up in output as:
The second <li> and the closing </ul> are rejected and escaped, then closing
</li> and </ul> get added at the end of the document.
Proper application of nesting rules *should* normalize it to
something like this: