Index: openacs-4/packages/acs-subsite/www/group-leave.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/acs-subsite/www/group-leave.tcl,v
diff -u -r1.2 -r1.3
--- openacs-4/packages/acs-subsite/www/group-leave.tcl	30 Jan 2004 15:17:31 -0000	1.2
+++ openacs-4/packages/acs-subsite/www/group-leave.tcl	27 Oct 2014 16:39:47 -0000	1.3
@@ -5,7 +5,7 @@
     @creation-date 2003-08-07
     @cvs-id $Id$
 } {
-    {group_id:integer {[application_group::group_id_from_package_id]}}
+    {group_id:naturalnum,notnull {[application_group::group_id_from_package_id]}}
     return_url:optional
 }
 
@@ -30,7 +30,7 @@
 
 }
 
-if { ![exists_and_not_null return_url] } {
+if { (![info exists return_url] || $return_url eq "") } {
     set return_url "../"
 }