Description of problem:
Satellite returns misleading error messages sometimes containing security sensitive information (e.g. account exists).

Version-Release number of selected component (if applicable):
spacewalk-backend-0.5.28-34.el5sat.noarch

How reproducible:
always

Steps to Reproduce:
1. run rhn_register
2. click through to 'Choose an update location' page
3. check 'Red Hat Network Satellite' and fill address of an existing satellite 5.3
4. fill wrong username/password and click Forward


Actual results:
depending whether username exists on satellite and password length error window says
 Error Class Code: 3
 Error Class Info: This login is already taken, or the password is incorrect.
or
 There was an error while logging in....
 and /var/log/up2date contains
  up2date_client.up2dateErrors.PasswordMinLengthError:
  Error Message:
    password must be at least 5 characters
or
 Error Class Code: 2001
 Error Class Info: 
     RHN Satellite user creation is not allowed via rhn_register...

Expected results:
The same error message which Hosted sends, i.e.
Error Class Code: 3
Error Class Info: The login or password is incorrect.

Additional info:
This is more generally about removing old register_user, new_user, etc. stuff which Hosted removed some time ago.