blockdev: fix drive_backup_prepare() missed error

We leak local_err and don't report failure to the caller. It's
definitely wrong, let's fix.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-Id: <20210202124956.63146-5-vsementsov@virtuozzo.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
1 file changed