boost 1.57 asio socket重复使用

去年用boost::asio::ip::tcp::socke(大概是boost 1.4.x版本）t时，服务器需要复用socket，socket关闭后，不能再accept,今天无聊中简单测试下，在1.5.7中似乎没问题。代码如下：

// TestC11.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include <iostream>
#include <memory>
#include <thread>
typedef std::shared_ptr<boost::asio::ip::tcp::socket> socket_ptr;

void clientSession(socket_ptr socket)
{
	while (true)
	{
		char buf[256];
		boost::system::error_code ec;
		size_t len;
			
		len = socket->read_some(boost::asio::buffer(buf), ec);

		write(*socket, boost::asio::buffer(buf, len));
		buf[len] = 0;
		std::cout << buf;
	}
}

int main(int argc, char **argv)
{
	boost::asio::io_service ios;
	boost::asio::ip::tcp::endpoint ep(boost::asio::ip::tcp::v4(), 2002);
	boost::asio::ip::tcp::acceptor acc(ios, ep);

	socket_ptr socket(new boost::asio::ip::tcp::socket(ios));
	while (1)
	{
		acc.accept(*socket);
		//std::thread t(&clientSession,