Make numericids defaults to null (fixes #3691)

ChangeLog

 version 1.0 -- UNRELEASED
     handler changes
+	rysnc:
+	 . Fix numericids option (Redmine#3691).
 	dup:
 	 . Make the .dup generated by ninjahelper more consistent with
 	   example.dup.

handlers/rsync.in

@@ -887,7 +887,7 @@ function set_filelist {
 
 function set_rsync_options {
 
-  if [ ! -z "$numericids" ]; then
+  if [ "$numericids" != "0" ]; then
     rsync_options="$rsync_options --numeric-ids"
   fi