Description:
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Last year we changed the structure of PHP manual.
 http://www.php.net/archive/2007.php#2007-10-03-1
The top page of each extension module became 'book.extname.php' instead of 'ref.extname.php', but php.net/extname still redirects to 'ref.extname.php'.
Now we have some extensions which doesn't have 'ref.extname.php' (e.g. PDO), so php.net/extname should redirect to 'book.extname.php' instead of 'ref.extname.php'.


Reproduce code:
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1. Set preferred language to 'Japanese'.
2. browse 'http://php.net/pdo'

Expected result:
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Redirect to Japanese documentation of PDO (http://php.net/manual/ja/book.pdo.php)

Actual result:
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Redirect to English documentation of PDO.