Fix $SYS/broker/version being incorrectly expired after 60 seconds.

Close #1245. Thanks to Christoph Krey.

ChangeLog.txt

@@ -10,6 +10,8 @@ Broker:
 - Fix Will message not allowing user-property properties.
 - Fix broker originated messages (e.g. $SYS/broker/version) not being
   published when `check_retain_source` set to true. Closes #1245.
+- Fix $SYS/broker/version being incorrectly expired after 60 seconds.
+  Closes #1245.
 
 Library:
 - Fix crash after client has been unable to connect to a broker. This occurs

src/sys_tree.c

@@ -52,7 +52,7 @@ void sys_tree__init(struct mosquitto_db *db)
 
 	/* Set static $SYS messages */
 	snprintf(buf, 64, "mosquitto version %s", VERSION);
-	db__messages_easy_queue(db, NULL, "$SYS/broker/version", SYS_TREE_QOS, strlen(buf), buf, 1, 60, NULL);
+	db__messages_easy_queue(db, NULL, "$SYS/broker/version", SYS_TREE_QOS, strlen(buf), buf, 1, 0, NULL);
 }
 
 static void sys_tree__update_clients(struct mosquitto_db *db, char *buf)