make update_log() work if zone is not set

- update_log() is called to log update errors, but if those errors
  occur before the zone is set (for example, when returning NOTAUTH)
  it returns without logging anything.

(cherry picked from commit 395f6a1474)

lib/ns/update.c

@@ -269,24 +269,34 @@ update_log(ns_client_t *client, dns_zone_t *zone,
 	char namebuf[DNS_NAME_FORMATSIZE];
 	char classbuf[DNS_RDATACLASS_FORMATSIZE];
 
-	if (client == NULL || zone == NULL)
+	if (client == NULL) {
 		return;
+	}
 
-	if (isc_log_wouldlog(ns_lctx, level) == false)
+	if (isc_log_wouldlog(ns_lctx, level) == false) {
 		return;
-
-	dns_name_format(dns_zone_getorigin(zone), namebuf,
-			sizeof(namebuf));
-	dns_rdataclass_format(dns_zone_getclass(zone), classbuf,
-			      sizeof(classbuf));
+	}
 
 	va_start(ap, fmt);
 	vsnprintf(message, sizeof(message), fmt, ap);
 	va_end(ap);
 
-	ns_client_log(client, NS_LOGCATEGORY_UPDATE, NS_LOGMODULE_UPDATE,
-		      level, "updating zone '%s/%s': %s",
-		      namebuf, classbuf, message);
+	if (zone != NULL) {
+		dns_name_format(dns_zone_getorigin(zone), namebuf,
+				sizeof(namebuf));
+		dns_rdataclass_format(dns_zone_getclass(zone), classbuf,
+				      sizeof(classbuf));
+
+		ns_client_log(client, NS_LOGCATEGORY_UPDATE,
+			      NS_LOGMODULE_UPDATE,
+			      level, "updating zone '%s/%s': %s",
+			      namebuf, classbuf, message);
+	} else {
+		ns_client_log(client, NS_LOGCATEGORY_UPDATE,
+			      NS_LOGMODULE_UPDATE,
+			      level, "%s", message);
+	}
+
 }
 
 static void