contrib: dracut: zfs-needshutdown: don't list

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Closes #13291

contrib/dracut/90zfs/zfs-needshutdown.sh.in

@@ -2,7 +2,7 @@
 
 command -v getarg >/dev/null 2>&1 || . /lib/dracut-lib.sh
 
-if zpool list 2>&1 | grep -q 'no pools available' ; then
+if [ -z "$(zpool get -Ho value name)" ]; then
     info "ZFS: No active pools, no need to export anything."
 else
     info "ZFS: There is an active pool, will export it."