I'm testing curious usernames, searching their `user_id` by:

http://api.stackoverflow.com/0.8/users/?filter=username_filter

i'm trying to get info about this particular user: 
http://stackoverflow.com/users/190597/unutbu

http://api.stackoverflow.com/0.8/users/?filter=unutbu  
returns nothing.

Any hints?  
The only thing i found is [this][1] meta post although i'm not sure  if it is related to the same problem.


  [1]: http://meta.stackoverflow.com/questions/44145/a-last-tribute-to-the-tilde