Request.Builder()
          .url(server.url("/"))
          .post(AsyncRequestBody())
          .build(),
      )
    val response2 = call.execute()

    // First duplex request is detached with violence.
    val requestBody1 = (call.request().body as AsyncRequestBody?)!!.takeSink()
    assertFailsWith<IOException> {
      requestBody1.writeUtf8("not authenticated\n")
      requestBody1.flush()