To replicate problem:
1) Navigate to cgi-bin/koha/patroncards/home.pl
2) Click 'New Batch' this will take you to cgi-bin/koha/patroncards/edit-batch.pl?op=new
3) Click 'Add Item(s)' -> opens pop up koha/patroncards/members-search.pl?batch_id=0
4) Search for a patron
5) Click 'add' on that borrower, edit-batch.pl updates to: cgi-bin/koha/patroncards/edit-batch.pl?op=add&batch_id=0&borrower_number=xxxxxx
the header on the edit-items screen shows "Items in batch number " ... this should read "Items in batch number YYYY" -- the batch number is not populated.
It is impossible to export the batch. Clicking back into manage batches *will* show a valid batch number and allow the batch to be exported, but we've broken the batch id on the batch creator page.
*** This bug has been marked as a duplicate of bug 14739 ***