API queries filtering on multiple contact_sub_type don't work

API queries which filter on multiple contact_sub_type's don't work when using multiple IN values.

CRM/Contact/Bao/Query.php #2872

foreach ($value as $k => $v) {
if (!empty($k))

{ $clause[$k] = "($alias $op '%" . CRM_Core_DAO::VALUE_SEPARATOR . CRM_Utils_Type::escape($v, 'String') . CRM_Core_DAO::VALUE_SEPARATOR . "%')"; }

}

It appears the values are passed to the function, however the array key of 0 is evaluated as empty, so only 1 condition is included in the search.