We have to reuse the query the user give us to generate the
pagination links.
At search result rendering step we don't have access to the query object.
The best place to know which arguments are used to select books
(and so which arguments to keep in the pagination links) is when we
parse the query to select books.
Fix tests (pagination links) with book selector other than "books.id="
(pattern=jazz&books.query.lang=eng)