When dns_request_create() fails in notify_send_toaddr() the TSIG key was
not cleared when retrying over TCP causing assertion failure. Set the
TSIG key to NULL in the dns_message to prevent the assertion failure.
(cherry picked from commit
ee3391a1460cd80b910136a65f44b6400b5e38fe)
cleanup:
if (result != ISC_R_SUCCESS) {
+ dns_message_settsigkey(message, NULL);
req_cleanup(request);
dns_request_detach(&request);
req_log(ISC_LOG_DEBUG(3), "%s: failed %s", __func__,