Link labels which are also standalone links are not correctly escaped

[http://www.xwiki.org>>http://www.xwiki.org]

in syntax 1.0 is transformed in

[[http://www.xwiki.org>>http://www.xwiki.org]]

in syntax 2.0,
which is rendered as invalid HTML (see XWIKI-3149) and causes problems on in the wysiwyg editor, for example, even if the browser recovers and displays that decently.

The 2.0 syntax result should be:

[[http:~~/~~/www.xwiki.org>>http://www.xwiki.org]]

, to correctly escape the link label.