Add a regression test for a problem where attempting to delete the
default subvolume would fail (as expected), but not until after all
submounts under the subvolume were unmounted.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
Reviewed-by: Eryu Guan <eguan@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Omar Sandoval