basic_socket_acceptor interface changed in boost 1.66... is this a mistake?

I found that between boost 1.65 and boost 1.66 the interface of basic_socket_acceptor is different. Check it here:

http://www.boost.org/doc/libs/1_65_0/doc/html/boost_asio/reference/basic_socket_acceptor/basic_socket_acceptor.html

http://www.boost.org/doc/libs/1_66_0/doc/html/boost_asio/reference/basic_socket_acceptor/basic_socket_acceptor.html

As you see at the end of the pages, the number of template parameters is different. Is this a mistake?