The return value should always be 0 if no problem happens, but
"btrfs filesystem show" executed on umounted device will always return 1
even there is no problem.
This testcase just checks it.
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Qu Wenruo