Bug 24113: guarantor info lost when a duplicate is found

Bug 24113: guarantor info lost when a duplicate is found

When a patron is created with a guarantor but a duplicate is found (or any other warnings I guess) the guarantor's info are lost.

This patch improves on previous functionality by retaining the select guarantor relationship as well.

Test Plan:
1) Create a new child with a name already used, add a guarantor
2) Attempt to save, no the guarantor is not shown when the editor is redisplayed
3) Apply this patch
4) Restart all the things!
5) Repeat 1
6) Note the guarantor is retained and the relationship is as well!

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>