Bug 14487: silence warns during checkin

Bug 14487: silence warns during checkin

Test plan
=========

1/ check out an item and then check it back in.
1/ check the logs after the check-in to see the warns from
   returns.pl line 623 of :
    (a) Use of uninitialized value $holdingBranch
    (b) Use of uninitialized value $collectionBranch
2/ apply patch
3/ check out and check-in again. no warns are recorded this time.

NOTE: Under Debian Jessie, there are other messages.
      Additionally, this only corrects the line 623 ones.

Signed-off-by: Mark Tompsett <mtompset@hotmail.com>
Signed-off-by: Nick Clemens <nick@quecheelibrary.org>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@unc.edu.ar>