*  Fix: Gracefully shut down the HTTP/2 connection before it exhausts the
    namespace of stream IDs (~536 million streams).
 *  Fix: Never pass a null `Route` to `Authenticator`. There was a bug where
    routes were omitted for eagerly-closed connections.

## Version 3.9.1

_2017-11-18_

 *  New: Recover gracefully when Android's DNS crashes with an unexpected
    `NullPointerException`.

    assertThat(response.body.string()).isEqualTo("abc")
    assertThat(server.takeRequest().sequenceNumber).isEqualTo(0)

    // Note that although we have two routes available, we only use one. The retry is permitted
    // because there are routes available, but it chooses the existing connection since it isn't
    // yet considered unhealthy.
    assertThat(server.takeRequest().sequenceNumber).isEqualTo(1)
  }