Bug 36793: Unit test

Bug 36793: Unit test

This only applies to 'local' preferences.

Test plan:
Run sysprefs.t with/without second patch.

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>
(cherry picked from commit b77cb006f1b1145b0251579e4122b7ad0c1bd0c1)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>
(cherry picked from commit d39200e0d631cf5f008cbd8d185319d847a595f7)
Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>