title: docker-compose up fails with "UnixHTTPConnectionPool(host='localhost', port=None): Pool is closed"
body: <p>I'm getting the following error when performing "docker-compose up". This seem to be a random problem. The version of docker-compose is "1.8.0, build f3628c7" and Linux version is "Linux 3.10.0-327.13.1.el7.x86_64". </p>
  
  <pre><code>  ERROR: for scheduler  UnixHTTPConnectionPool(host='localhost', port=None): Pool is closed.
  Traceback (most recent call last):
    File "&lt;string&gt;", line 3, in &lt;module&gt;
    File "compose/cli/main.py", line 61, in main
    File "compose/cli/main.py", line 113, in perform_command
    File "compose/cli/main.py", line 835, in up
    File "compose/project.py", line 400, in up
    File "compose/parallel.py", line 64, in parallel_execute
  requests.packages.urllib3.exceptions.ClosedPoolError: UnixHTTPConnectionPool(host='localhost', port=None): Pool is closed.
  </code></pre>
  
  <p>Although this issue is reported in docker github page, no insight into the resolution of the issue is mentioned. Any help to resolve this issue is appreciated. </p>