zfs-import-{cache,scan}: change condition to FileNotEmpty

When all pools are exported ZFS will generate an empty cache file.
This will cause the import service to fail, which is sub-optimal, 
since this means that dracut fails, and it necessary to run 
`zpool import -a` to boot, delete the file, and regenerate+reinstall 
the initrd.

This resolves the issue by treating an zero-length cache files the
same as a missing cache file.  This aligns the behavior with that
of the `zpool` command itself.

Reviewed-by: Brian Behlendorf <[email protected]>
Reviewed-by: Richard Laager <[email protected]>
Signed-off-by: Ahelenia Ziemiańska <[email protected]>
Closes #11568 

0 files changed, 0 insertions, 0 deletions