Bug 18442: Fix DB user loggin

Test plan:
1. Drop and recreate your db

2. Clear memcached

3. Go through the installer (to speed up this test plan install all
sample data so you dont have to create libraries, patron categories etc. later)

4. On the installer page login as the database user and notice that it
does not work on the first attempt ( you get 'Error: You do not have
permission to access this page')

5. Try logging in as database user for a second time and notice you are
logged in successfully this time

4. In staff interface create a patron account with superlibrarian permissions

5. Logout of the staff interface

6. Login as database user

7. Notice you cant log in. You get the 'Error:: You do not have permission to access this
page' error

8. Try a second attempt and notice you get the same error

9. Open the URL in a new tab and notice the staff interface appears
showing that you are logged in

10. log out and log back in as the superlibrarian user you created and
notice it works on first login attempt

11. Apply patch

12. Log out and try logging back in as database user and notice that you
can login successfully on first attempt

13. Repeat steps 1,2,3 and login as database user and notice the login
works on first attempt

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>

Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>

C4/Auth.pm

@@ -1021,6 +1021,7 @@ sub checkauth {
 
             # $return: 1 = valid user, 2 = superlibrarian
             if ($return) {
+                $userid ||= $q_userid if $return == 2;
 
                 #_session_log(sprintf "%20s from %16s logged in  at %30s.\n", $userid,$ENV{'REMOTE_ADDR'},(strftime '%c', localtime));
                 if ( $flags = haspermission( $userid, $flagsrequired ) ) {