Bug 26270: Fix ThingISBN after a change in behaviour

Bug 26270: Fix ThingISBN after a change in behaviour

This is just a guess! One of our tests is failing since today and we
don't modify anything in this area.
My guess is that the service is now returning the normalized version of
the ISBN

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
(cherry picked from commit fe529e3324405b30329054b9e8125babc357e1fe)

Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>