use pack to construct the reply as Net::DNS just get it wrong

bin/tests/system/resolver/ans8/ans.pl

@@ -76,18 +76,15 @@ sub handleUDP {
 		return $packet->data;
 	}
 
-	# Ensure the QUESTION section is empty in the response.
-	$packet->pop("question");
+	# don't use Net::DNS to construct the header only reply as early
+	# versions just get it completely wrong.
 
 	if ($qname eq "truncated.no-questions") {
-		$packet->header->tc(1);
+		# QR, AA, TC
+		return (pack("nnnnnn", $packet->header->id, 0x8600, 0, 0, 0, 0));
 	}
-
-	# Net::DNS versions < 0.68 insert an ./ANY RR into the QUESTION section
-	# if the latter is empty.  Make sure Net::DNS version does not
-	# influence the return value of this function by returning the query ID
-	# and flags generated by Net::DNS with 8 zero bytes appended.
-	return substr($packet->data, 0, 4) . "\x00" x 8;
+	# QR, AA
+	return (pack("nnnnnn", $packet->header->id, 0x8400, 0, 0, 0, 0));
 }
 
 sub handleTCP {