Bug 22219: Remove duplicated items in inventory (when skipping waiting holds)

Bug 22219: Remove duplicated items in inventory (when skipping waiting holds)

Test plan:
0/ Do not apply this patch
1/ Place several holds on a given item
2/ Use the inventory with the "skip waiting holds" option to list this item.
It will be displayed several times
3/ Apply this patch and confirm that the item is now only displayed once

Signed-off-by: Pierre-Marc Thibault <pierre-marc.thibault@inLibro.com>

Signed-off-by: Josef Moravec <josef.moravec@gmail.com>

Signed-off-by: Nick Clemens <nick@bywatersolutions.com>