[type/__uci] Only generate __uci_commit if changes are required

cdist/conf/type/__uci/manifest

@@ -18,9 +18,12 @@
 # along with cdist. If not, see <http://www.gnu.org/licenses/>.
 #
 
+in_list() { printf '%s\n' "$@" | { grep -qxF "$(read -r ndl; echo "${ndl}")"; } }
 
 os=$(cat "${__global:?}/explorer/os")
 
+state_is=$(cat "${__object:?}/explorer/state")
+state_should=$(cat "${__object:?}/parameter/state")
 transaction_name=$(cat "${__object:?}/parameter/transaction")
 
 case ${os}
@@ -35,6 +38,25 @@ in
 		;;
 esac
 
+changes_required=false
 
-# Make sure the changes are being commited
+case ${state_should}
+in
+	(present)
+		# NOTE: order is ignored so rearranged is also fine.
+		in_list "${state_is}" 'present' 'rearranged' || changes_required=true
+		;;
+	(absent)
+		in_list "${state_is}" 'absent' || changes_required=true
+		;;
+	(*)
+		printf 'Invalid --state: %s\n' "${state_should}" >&2
+		exit 1
+		;;
+esac
+
+if ${changes_required}
+then
+	# Make sure the changes are being committed
 	require=${__object_name:?} __uci_commit "${transaction_name}"
+fi