if (!shash_add_once(&new_ifaces, if_cfg->name, NULL)) {
VLOG_WARN("port %s: %s specified twice as port interface",
port->name, if_cfg->name);
if (!shash_add_once(&new_ifaces, if_cfg->name, NULL)) {
VLOG_WARN("port %s: %s specified twice as port interface",
port->name, if_cfg->name);