--- mdadm.install.orig	2012-01-23 09:36:10.000000000 +0100
+++ mdadm.install	2012-01-23 09:36:38.000000000 +0100
@@ -2,7 +2,7 @@
 # arg 2:  the old package version

 post_upgrade() {
-  if [ "$(vercmp $2 2.6.8-2)" -lt 0 -a "$(grep raid_partitions /etc/mkinitcpio.conf)" ]; then
+  if [ "$(vercmp $2 2.6.8-2)" -lt 0 -a "$(grep -s raid_partitions /etc/mkinitcpio.conf)" ]; then
     echo "Attention mdadm update:"
     echo "raid_partitions hook has been replaced by the more powerfull mdadm hook."
     echo "Please update your /etc/mkinitcpio.conf accordingly."