Bug 26627: Print and confirming a hold can cause an infinite loop

Bug 26627: Print and confirming a hold can cause an infinite loop

Test plan:
1) Place a hold for pickup at library A
2) Confirm the hold and print slip
3) Checkin the item again
4) Confirm the hold and print slip
5) The modal returns, do it again
6) Apply this patch
7) Reload the page
8) Repeat steps 1-3
9) No loop!

Signed-off-by: Séverine QUEUNE <severine.queune@bulac.fr>
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 a71596fb395d449a62f5a6417780ed23948755c4)

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