Bug 27330: (QA follow-up) Return 409 instead

Bug 27330: (QA follow-up) Return 409 instead

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
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 fd272244157ad0dc5e83a0cfb6430bbf1d3b90c8)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>
(cherry picked from commit fd75ab1808940704f9a1445d14d43198e501040d)

Signed-off-by: Andrew Fuerste-Henry <andrew@bywatersolutions.com>