Commit955c1f881a(v17.12.0) replaced detection of support for multiple lowerdirs (as required by overlay2) to not depend on the kernel version. The `overlay2.override_kernel_check` was still used to print a warning that older kernel versions may not have full support. After this,e226aea280(v20.10, but backported to v19.03.7) removed uses of the option altogether. Signed-off-by: Sebastiaan van Stijn <github@gone.nl>