supporting overlay+tmpfs breaks check -n -overlay -g auto

[Murphy Zhou <jencce.kernel@xxxxxxxxx>]

Hi,

Bisecting points me to this commit:

commit 92fb58afaa2f38a9369ad5791a4cbf135545617d
Author: Baokun Li <libaokun1@xxxxxxxxxx>
Date:   Wed May 11 16:34:04 2022 +0800

    common: xfstests support overlay+tmpfs


It breaks this command:
./check -n -overlay -g auto

As a result, it fails to show me the list of testcases.

Please help to check.

Thanks!
Murphy