SSHMUX_VER
(r = sshbuf_put_u32(out, SSHMUX_VER)) != 0)
(r = sshbuf_put_u32(m, SSHMUX_VER)) != 0)
if (ver != SSHMUX_VER) {
"(expected %d)", ver, SSHMUX_VER);
if (ver != SSHMUX_VER) {
"(expected %u)", ver, SSHMUX_VER);