Fix extensible_parallel_list_field selector so the event tha duplicates fields only fires for the actual element providing the extensible_parallel_list_field CSS class, instead of it also being fired for siblings that didn't implement that class but which were under the same "input" CSS class.

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@41449 20353a03-c40f-0410-a6d1-a30d3c3de9de