Except for ssh.exe in openssh, any other console program runs very well.

```cpp
namespace bp = boost::process;
BOOST_AUTO_TEST_CASE(stackful, *boost::unit_test::timeout(1500))
{
using boost::unit_test::framework::master_test_suite;
bool did_something_else = false;
boost::asio::io_service ios;
boost::process::async_pipe StdOutPipe(ios);
auto stackful =
[&](boost::asio::yield_context yield_)
{
int ret =
bp::async_system(
ios, yield_,boost::process::windows::hide,
"C:/Program Files/OpenSSH/bin/ssh.exe localhost "
,boost::process::std_out > StdOutPipe
);
};

boost::asio::spawn(ios, stackful);
ios.post([&] {did_something_else = true; });

ios.run();
BOOST_CHECK(did_something_else);
}
```

program always crash at

```
file：win_iocp_io_service.ipp ：
function：size_t win_iocp_io_service::do_one(bool block, boost::system::error_code& ec)
line 390 : op->Internal = reinterpret_cast(&result_ec.category());
```

OS：win10
boost version：boost_1_69_0
c++ compliler：vc2017 x86
openssh version：setupssh-7.9p1-1

help me if I did anything wrong;
thank a lot！