Index: wp-admin/css/wp-admin.dev.css
===================================================================
--- wp-admin/css/wp-admin.dev.css	(revision 19312)
+++ wp-admin/css/wp-admin.dev.css	(working copy)
@@ -1853,6 +1853,10 @@
 	margin-bottom: 1px;
 }
 
+.folded #adminmenu .wp-has-current-submenu.menu-top-last {
+	margin-bottom: 0;
+}
+
 .folded #adminmenu .wp-has-current-submenu .wp-submenu-wrap {
 	margin-top: 4px;
 }