Book Module - Weights not Respected

Confirmed, with the following book contents:

* My Book
This is the root node of my book.
* Shrubs
Section 1, weight 0
* Yew hedges
Subsection 1.1, weight 0
* Cedar hedges
Subsection 1.2, weight 1
* Buildings
Section two, weight 1
* Three storey apartment blocks
Subsection 2.1, weight 0
* Duplexes
Subsection 2.2, weight 1
* Automobiles
Third section, weight 2
* Sub-compact
Subsection 3.1, weight 0
* Minivan
Subsection 3.2, weight 1
* Commuter car
Subsection 3.3, weight 2

The attached patch to book.module ensures that a book node's weight is captured when the book node lists returned by book_location() and book_location_down() are generated. This information is required when selecting previous/next page candidates in book_next() and book_prev().

Note that book_location_down() was missing an explicit field b.weight in the SQL SELECT statement, but this value would usually be supplied implicitly because it is used to ORDER the result.

Committed to DRUPAL-4-5 and HEAD. I think it is only necessary for book_next(), not for book_prev() though.