bail early if the list is empty - eg if the cache has all the URNs we are validating, don't query for an empty list of URNs - 7 fixes in guard_utils
bail early if the list is empty - eg if the cache has all the URNs we are validating, don't query for an empty list of URNs - 7 fixes in guard_utils

tcmitchell/geni-ch,ahelsing/geni-ch,tcmitchell/geni-ch,MarshallBrinn/geni-ch,ahelsing/geni-ch,MarshallBrinn/geni-ch