no warning message when creating new user with duplicated username

[GoogleCodeExporter]

1. go to the management interface
2. select 'Users'
3. click 'Add'
4. create a new user with a duplicated username
5. click 'Save'

The expected output should be:
 - the user is not created
 - a warning message is presented

However, although the user is not created, no warning message is presented and 
the user creation form is not closed.

Original issue reported on code.google.com by maurizio...@gmail.com on 16 Feb 2011 at 10:22

[GoogleCodeExporter]

Original comment by fabrizio.solinas83@gmail.com on 28 Jun 2011 at 8:33

• Changed state: Fixed

[GoogleCodeExporter]

Original comment by maurizio...@gmail.com on 26 Oct 2011 at 4:19

• Changed state: Accepted

[GoogleCodeExporter]

Original comment by maurizio...@gmail.com on 26 Oct 2011 at 4:28

• Changed state: Verified