Boost MPI doesn't free resources when listening for lists?

This is a follow-on question to How do I free a boost::mpi::request? . I'm noting odd behavior when listening for lists rather than individual items. Is this my error or an error in boost? I'm using MSVC and MSMPI, Boost 1.62. I'm pretty sure that it's not behaving properly on the wait for a cancelled job.

If you try version B with mpiexec -n 2 then you get a clean exit - if you try version A, it hangs indefinitely. Do you all see this as well? Is this a bug?

#include "boost/mpi.hpp"
#include "mpi.h"
#include <list>
#include "boost/serialization/list.hpp"

int main()
{
    MPI_Init(NULL, NULL);
    MPI_Comm regional;
    MPI_Comm_dup(MPI_COMM_WORLD, &regional);
    boost::mpi::communicator comm = boost::mpi::communicator(regional, boost::mpi::comm_attach);
    if (comm.rank() == 1)
    {


        //VERSION A:
        std::list<int> q;
        boost::mpi::request z = comm.irecv<std::list<int>>(1, 0, q);
        z.cancel();
        z.wait();


        //VERSION B:
//      int q;
//      boost::mpi::request z = comm.irecv<int>(1, 0, q);
//      z.cancel();
//      z.wait();

    }
    MPI_Comm_disconnect(&regional);
    MPI_Finalize();
    return 0;
}