Bug 24106: In returns.pl, don't search for item if no barcode is provided

Bug 24106: In returns.pl, don't search for item if no barcode is provided

When loading returns.pl, code to check rotating collections fires off an search for items by barcode, but doesn't check for a barcode first. This means the code will search for items where barcode is NULL, which is definitely not the intended function.

Test Plan:
1) Apply this patch
2) Set up a rotating collection with items
3) Transfer the collection
4) Check in a rotating collection item
5) Note no change in functionality

Signed-off-by: Liz Rea <wizzyrea@gmail.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>