Nested definition lists don't appear nested

Nested definition list syntax doesn't produce a nested definition list; the structure is flat.

Using this syntax:

; term 1
: definition 1
:; term 2
:: definition 2

This can be seen on http://platform.xwiki.org/xwiki/bin/view/XWiki/XWikiSyntax?syntax=2.1&section=DefinitionLists