aleph seems to hang

gistfile1.clj

(defproject alephplay "0.1.0-SNAPSHOT"
  :description "FIXME: write description"
  :url "http://example.com/FIXME"
  :license {:name "Eclipse Public License"
            :url "http://www.eclipse.org/legal/epl-v10.html"}
  :dependencies [[org.clojure/clojure "1.7.0-alpha4"]
                 [aleph "0.4.0-alpha9" :exclusions [org.clojure/clojure]]])


(ns alephplay.core
  (:require
   [aleph.http :as http]
   [manifold.deferred :as d]))

(def server
  (http/start-server
   (fn [req]
     (d/let-flow [status (future 200)]
                 {:status status :body "Hello World!"}))
   {:port 8080}))

;; This works on the first connection to 8080, but the client hangs on every subsequent connection.

$ curl -i localhost:8080
HTTP/1.1 200 OK
Server: Aleph/0.4.0
Connection: Keep-Alive
Date: Mon, 22 Dec 2014 14:35:26 GMT
Content-Length: 12

Hello World!
$ curl -i localhost:8080