[gdm] daemon: don't allow worker manager interface to be unexported more than once

[Ray Strode <halfline src gnome org>]

commit 9181419e471acbc0b3600eacd0c4513830a76ea3
Author: Ray Strode <rstrode redhat com>
Date:   Tue Sep 30 13:17:22 2014 -0400

    daemon: don't allow worker manager interface to be unexported more than once
    
    if a conversation is stopped asynchronously and then synchronously, we
    will end up trying to unexport the bus interface more than once, leading
    to log spew.
    
    This commit protects against that.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=737391

 daemon/gdm-session.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/daemon/gdm-session.c b/daemon/gdm-session.c
index 406e42e..319b363 100644
--- a/daemon/gdm-session.c
+++ b/daemon/gdm-session.c
@@ -1871,6 +1871,7 @@ close_conversation (GdmSessionConversation *conversation)
 
         if (conversation->worker_manager_interface != NULL) {
                 unexport_worker_manager_interface (self, conversation->worker_manager_interface);
+                g_clear_object (&conversation->worker_manager_interface);
         }
 
         if (conversation->worker_proxy != NULL) {