[empathy: 5/9] Throw a warning if the contact sort function didn't get two contacts

[Danielle Madeley <daniellem src gnome org>]

commit 813e42dcf617f97e0ed0cdc7a77ad428d5b87ef2
Author: Sjoerd Simons <sjoerd simons collabora co uk>
Date:   Sat Jun 19 20:05:43 2010 +0100

    Throw a warning if the contact sort function didn't get two contacts

 libempathy-gtk/empathy-contact-list-store.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/libempathy-gtk/empathy-contact-list-store.c b/libempathy-gtk/empathy-contact-list-store.c
index 5776899..8916761 100644
--- a/libempathy-gtk/empathy-contact-list-store.c
+++ b/libempathy-gtk/empathy-contact-list-store.c
@@ -1573,6 +1573,8 @@ contact_list_store_contact_sort (EmpathyContact *contact_a,
 	TpAccount *account_a, *account_b;
 	gint ret_val;
 
+	g_return_val_if_fail (contact_a != NULL || contact_b != NULL, 0);
+
 	/* alias */
 	ret_val = g_utf8_collate (empathy_contact_get_name (contact_a),
 				  empathy_contact_get_name (contact_b));