buxtond: Fix consistency of notification lists
buxtond: Fix consistency of notification lists

Appending an item to a list doesn't modify it's first element
but removing an item may modify that first element. Thus
taking it into account in `unregister_notification` does matter.

Signed-off-by: José Bollo <08496fd66cc394b517cafa0b18bcb9ce79fe4230@open.eurogiciel.org>

sofar/buxton,sofar/buxton