dom0-updates: fix command quotation, hide only harmless error msgs

dom0-updates/qubes-dom0-update

@@ -80,7 +80,7 @@ echo "Using $UPDATEVM as updatevm to download updates for Dom0, this may take so
 # Start VM if not running already
 qvm-run $QVMRUN_OPTS -a $UPDATEVM true || exit 1
 
-tar c /var/lib/rpm /etc/yum.repos.d /etc/yum.conf 2>/dev/null | qvm-run -p "$UPDATEVM" tar x -C /var/lib/qubes/dom0-updates 2> /dev/null
+tar c /var/lib/rpm /etc/yum.repos.d /etc/yum.conf 2>/dev/null | qvm-run -p "$UPDATEVM" 'tar x -C /var/lib/qubes/dom0-updates'
 
 qvm-run $QVMRUN_OPTS --pass-io $UPDATEVM "/usr/lib/qubes/qubes-download-dom0-updates.sh --doit --nogui $ALL_OPTS"
 RETCODE=$?