[goffice] don't crash when destroying a group

[Jean Bréfort <jbrefort src gnome org>]

commit 183aa2b665f32fe1b0473d2713a11dccdfee8d1d
Author: Jean Brefort <jean brefort normalesup org>
Date:   Wed Aug 26 16:49:38 2009 +0200

    don't crash when destroying a group

 ChangeLog                  |    5 +++++
 goffice/canvas/goc-group.c |    1 +
 2 files changed, 6 insertions(+), 0 deletions(-)
---
diff --git a/ChangeLog b/ChangeLog
index 6b75809..53b0698 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,10 @@
 2009-08-26  Jean Brefort  <jean brefort normalesup org>
 
+	* goffice/canvas/goc-group.c (goc_group_finalize): don't crash when
+	destroying a group.
+
+2009-08-26  Jean Brefort  <jean brefort normalesup org>
+
 	* goffice/gtk/go-combo-box.c (go_combo_box_set_display): expand the
 	 display widget.
 	* goffice/gtk/go-format-sel.c (nfs_init): create missing combo box.
diff --git a/goffice/canvas/goc-group.c b/goffice/canvas/goc-group.c
index 85fb7c9..3449e55 100644
--- a/goffice/canvas/goc-group.c
+++ b/goffice/canvas/goc-group.c
@@ -221,6 +221,7 @@ goc_group_finalize (GObject *obj)
 		l = g_list_next (l);
 	}
 	g_list_free (group->children);
+	group->children = NULL;
 	(parent_klass->finalize) (obj);
 }