Bug 27837: Permanent location to be empty string, check if key exists

Bug 27837: Permanent location to be empty string, check if key exists

Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
(cherry picked from commit aa1d86920bd0392b4894fa2e756dcb41f2f7a5ec)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>
(cherry picked from commit bdbd2c7225f347ab23770b0b09f8f86816353ada)

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