Detect signature by anoymous users

[phauly]

getCollaborators() method of mwlib.py looks for
[[User:nome|testo lungo]].

It does not work for signatures made by anonymous users
Example, at the end of http://en.wikipedia.org/wiki/User_talk:Phauly there is the following text

Just a test done by myself on signature formatting.
--[[Special:Contributions/217.77.80.29|217.77.80.29]]([[User
talk:217.77.80.29|talk]]) 12:08, 8 February 2010 (UTC)
February 2010 (UTC)