remove unused variable warning

src/knot/server/zones.c

@@ -1064,7 +1064,6 @@ static int zones_insert_zone(conf_zone_t *z, knot_zone_t **dst,
 	}
 
 	/* Reload zone file. */
-	int is_new = 0;
 	int ret = KNOT_ERROR;
 	if (zone_changed) {
 		/* Zone file not exists and has master set. */
@@ -1102,7 +1101,6 @@ static int zones_insert_zone(conf_zone_t *z, knot_zone_t **dst,
 				}
 				log_server_info("Loaded zone '%s' serial %u\n",
 				                z->name, (uint32_t)sn);
-				is_new = 1;
 			}
 		}