Bug 31154: (QA follow-up) Fix UI form builder

Bug 31154: (QA follow-up) Fix UI form builder

The change in batchMod.pl is not needed when we fix the builder.
But we could at least add a comment there!

Note that passing the biblionumber of the first item does not
make sense since we are modifying items from several biblio
records normally. We most probably do not want this MARC
record's itemcallnumber (via the syspref) in all our items.

Test plan:
Test batchMod with and without the Populate fields checkbox.
Fill syspref 'itemcallnumber' with e.g. 084a.
Check Populate, and try again.

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>