Fix Glib warning

Upgrade process generates the following warning message from GLib:

GLib-GObject-CRITICAL **: 10:36:30.622: g_object_unref: assertion 'G_IS_OBJECT (object)' failed

GIO takes care of cleaning up the result and error information after the GAsyncReadyCallback returns, see https://developer.gnome.org/gio/stable/GAsyncResult.html.

Signed-off-by: Frédéric Danis frederic.danis@collabora.com