It makes sense to use items by branch to get the list of branches, as it
already tells use which branches have available items. We could use
branches to pull from instead, but all we would accomplish is added
extra ununsed loop iterations. We already know that any additional
branches in the branches to pull loop have no items to fill holds.
If they did, they would be in the items_by_branch hash.
Signed-off-by: David Nind <david@davidnind.com> Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com> Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>