Bug 25608: (bug 23463 follow-up) Fix inventory regression

Bug 25608: (bug 23463 follow-up) Fix inventory regression

Follow-up work
  commit bbb504c86f5ca0a474365d4839177412f415c4ee
  Bug 23463: Replace ModItem with Koha::Item->store

Test plan :
    - Create a biblio with default framework
    - Create an item with barcode='000AAA1', callnumber='ZZZAAA1'
    - Create an item with barcode='000AAA2', callnumber='ZZZAAA2'
    - Create a file 'barecodes.txt' containing 2 lines '000AAA1' and '000AAA2'
    - Go to inventory tool : /cgi-bin/koha/tools/inventory.pl
    - Choose file in 'Barcode file'
    - Enter item callnumber between 'ZZZ' and 'ZZZa'
    - Check 'Compare barcodes list to results'
    - Submit
    => without patch, you get an error trace
    - Apply patch, it works

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Amended commit title.
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>