Skip empty non terminals in _find_parent_helper. Fixes   ok($dns->find_parent("narnia.pp.se", "IN") eq "se"); in t/find_parent.t
Skip empty non terminals in _find_parent_helper.
Fixes
  ok($dns->find_parent("narnia.pp.se", "IN") eq "se");
in t/find_parent.t

NZRS/dnscheck,NZRS/dnscheck,dotse/dnscheck,NZRS/dnscheck,NZRS/dnscheck,NZRS/dnscheck,dotse/dnscheck,dotse/dnscheck,dotse/dnscheck,dotse/dnscheck,NZRS/dnscheck,dotse/dnscheck