[gdm] greeter: Fix double free on timed login

[Ray Strode <halfline src gnome org>]

commit b83273f28cbecb7101020eaa9d06445d7267df1d
Author: Jürg Billeter <j bitron ch>
Date:   Fri May 20 13:40:36 2011 +0200

    greeter: Fix double free on timed login

 gui/simple-greeter/gdm-chooser-widget.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/gui/simple-greeter/gdm-chooser-widget.c b/gui/simple-greeter/gdm-chooser-widget.c
index e81bd77..ca27fc1 100644
--- a/gui/simple-greeter/gdm-chooser-widget.c
+++ b/gui/simple-greeter/gdm-chooser-widget.c
@@ -2462,6 +2462,7 @@ gdm_chooser_widget_lookup_item (GdmChooserWidget *widget,
 
         if (active_item_id == NULL || strcmp (active_item_id, id) != 0) {
                 g_free (active_item_id);
+                active_item_id = NULL;
 
                 if (!find_item (widget, id, &iter)) {
                         return FALSE;