shutils: return proper error in {do,pre,post}_* stage funcs and use msg_error.

--HG--
extra : convert_revision : xtraeme%40gmail.com-20091012220713-k3j00b7x3jk5s3we

shutils/common_funcs.sh

@@ -33,7 +33,10 @@ run_func()
 	[ -z "$func" ] && return 1
 
 	type -t $func | grep -q 'function'
-	[ $? -eq 0 ] && $func
+	if [ $? -eq 0 ]; then
+		$func
+		return $?
+	fi
 }
 
 run_rootcmd()