Do not try to backlist and do not try DNS failover for blind UACs as

they do not have a destination address.

modules/tm/timer.c

@@ -449,7 +449,9 @@ inline static void final_response_handler(	struct retr_buf* r_buf,
 	DBG("DEBUG: final_response_handler:stop retr. and send CANCEL (%p)\n", t);
 #endif
 	if ((r_buf->branch < MAX_BRANCHES) && /* r_buf->branch is always >=0 */
-			(t->uac[r_buf->branch].last_received==0)){
+			(t->uac[r_buf->branch].last_received==0) &&
+			(t->uac[r_buf->branch].request.buffer!=NULL) /* not a blind UAC */
+	){
 		/* no reply received */
 #ifdef USE_DST_BLACKLIST
 		if (cfg_get(core, core_cfg, use_dst_blacklist)