zmq set_metadata crash repro

gistfile1.txt

daveo@abraxas:~/zmq-crash-repro$ more server.c client.c 
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server.c
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// invoked as valgrind ./server
#include <zmq.h>

void main(void) {
    void *ctx = zmq_ctx_new();
    void *socket = zmq_socket(ctx, ZMQ_XPUB);
    int one = 1;
    char *secret_key = "2).NRO5d[JbEFli7F@hdvE1(Fv?B6iIAn>NcLLDx";
    zmq_setsockopt(socket, ZMQ_CURVE_SERVER, &one, sizeof(one));
    zmq_setsockopt(socket, ZMQ_CURVE_SECRETKEY, secret_key, 40);
    zmq_bind(socket, "tcp://*:9999");

    while (1) {
        char buf[256];
        zmq_recv(socket, buf, 256, 0);
        //if (buf[0] == 1) fprintf(stderr, "got %s\n", buf + 1);
    }
}
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client.c
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// run as: while ./client; do :; done
#include <zmq.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>

// Magic constant, needs to be sufficient time to get the server processing
// the subscription but then exit before it's done.  Curve is used only
// because it adds time and cost to the equation, and probably is not a
// functioning part of error.  This value was narrowed down based on the
// behavior of my computer and with the server running in valgrind
#define DELAY 28000

void main(void) {
    void *ctx = zmq_ctx_new();
    void *socket = zmq_socket(ctx, ZMQ_SUB);
    char *sub = "subscription";
    char public_key[41], private_key[41];
    char *server_key = "^kvy<i^qI<r{=ZDrfK4K<#NtqY+zaH:ksm/YGE6I";
    zmq_curve_keypair(public_key, private_key);
    zmq_setsockopt(socket, ZMQ_CURVE_SERVERKEY, server_key, 40);
    zmq_setsockopt(socket, ZMQ_CURVE_PUBLICKEY, public_key, 40);
    zmq_setsockopt(socket, ZMQ_CURVE_SECRETKEY, private_key, 40);
    zmq_connect(socket, "tcp://localhost:9999");
    zmq_setsockopt(socket, ZMQ_SUBSCRIBE, sub, strlen(sub));
    usleep(rand() % DELAY);
}