Bug 12226 - A user with the database username/userid can access staff with full permi...

Bug 12226 - A user with the database username/userid can access staff with full permissions

This patch implements 2 suggestions on comment #3

- Prevents creation of a new user with same userid
of database user

- When checking password, if userid matches database user,
only check against pass on config file

To test:
1. Create a new user with same login as database user
any password different from real db user
2. Check that you can login on staff using this user/pass
and you are superlibrarian

3. Apply the patch

4. Login again using new pass, it must fail
5. Login again using db pass, you are now superuser,
but system does not warn you :( No problem, that's
for having one borrower with that login
6. Delete user with same login as db user
7. Try to create one again as in 1, system must return
an error of duplicate login!

8. Check for no regressions on user/pass authentication

Resubmited, has an error

Signed-off-by: Chris Cormack <chrisc@catalyst.net.nz>
Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
Passes all tests and QA script.
This works nicely and as described.
Also editing the former 'superuser' will force you to
change the userid in order to save any other change.

Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>