Bug 31908: Add a test to show issue

Bug 31908: Add a test to show issue

Test plan:
Without next patch, run Auth.t.
Should fail now before next patch resolves problem:
    not ok 2 - Login of patron2 approved
    ok 3 - Did not return previous session ID
    not ok 4 - New session ID not empty

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: David Cook <dcook@prosentient.com.au>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Wainui Witika-Park <wainuiwitikapark@catalyst.net.nz>