commit 15cce0a5bc2d659db7938f5b691ad1abfa496db1
Author: Sam Spilsbury <smspillaz@gmail.com>
Date:   Tue Aug 8 16:42:58 2017 +0800

    settings: Make sure to set old settings global to NULL on finalize

diff --git a/common/gdm-settings.c b/common/gdm-settings.c
index 1040fbba..88b079bf 100644
--- a/common/gdm-settings.c
+++ b/common/gdm-settings.c
@@ -187,6 +187,8 @@ gdm_settings_finalize (GObject *object)
                 g_object_unref (settings->priv->backend);
         }
 
+        settings_object = NULL;
+
         G_OBJECT_CLASS (gdm_settings_parent_class)->finalize (object);
 }
 
