The previous version was returning the list of pages to be fetched, but
we are going to need an efficient membership test (i.e. is the page
$title tracked), hence exposing a hash will be more convenient.
Signed-off-by: Matthieu Moy <Matthieu.Moy@imag.fr> Signed-off-by: Junio C Hamano <gitster@pobox.com>