confile: don't leak memory when overwriting lxc.rootfs.options

src/lxc/confile.c

@@ -2465,6 +2465,10 @@ static int set_config_rootfs_options(const char *key, const char *value,
 	struct lxc_rootfs *rootfs = &lxc_conf->rootfs;
 	int ret;
 
+	clr_config_rootfs_options(key, lxc_conf, data);
+	if (lxc_config_value_empty(value))
+		return 0;
+
 	ret = parse_mntopts(value, &mflags, &mdata);
 	if (ret < 0)
 		return ret_errno(EINVAL);