vzmigrate: don't use ploop snapshot-list -s

Option -s of ploop snapshot-list only appeared in ploop 1.11,
and we can't expect it to be available (nor it makes sense to
depend on it for this option).

So, just drop -s option and filter out the top delta filename
using sed.

Signed-off-by: Kir Kolyshkin <kir@openvz.org>
1 file changed