[Bug 49296] Don't accept underscore "_" in usernames

[m_ax]

Public bug reported:

Binary package hint: user-setup

As i was installing my ubuntu, I found out, that i am not able to use my native username "m_ax". So I continued installing with username "max". Than I changed my login in /etc/passwd, /etc/shadow and /etc/group to m_ax. But even when I open "Users and Groups" from Administration menu, edit my(m_ax) preferences, and click OK, I get error: Username have invalid characters. 
Before I was able to switch to "m_ax" name, i also tried adding line:
NAME_REGEX="([a-zA-Z][_a-z]+){2,}"
to /etc/adduser.conf
After this step, I was able to add usernames with underscores "_" to names, but gnome "Users and Groups" still not in friedship with me :(
Regards

** Affects: gnome-system-tools (Ubuntu)
     Importance: Low
     Assignee: Ubuntu Desktop Bugs
         Status: Confirmed

-- 
Don't accept underscore "_" in usernames
https://launchpad.net/bugs/49296