title: Docker inside docker : volume is mounted, but empty
body: <p>I am running a docker container with docker mounted inside using :</p>
  
  <pre><code>docker run -v /Path/to/service:/src/service -v /var/run/docker.sock:/var/run/docker.sock --net=host image-name python run.py
  </code></pre>
  
  <p>This runs a python script that creates a <code>data</code> folder in <code>/src</code> and fills it. When printing <code>os.listdir('/src/data')</code>, I get a list of files.</p>
  
  <p>I then run a container from within this container, mounting the <code>data</code> folder, using <code>docker-py</code>.</p>
  
  <pre><code>volumes = {'/src/data': {'bind': '/src', 'mode': 'rw'}}    
  client.containers.run(image, command='ls data', name=container_key, network='host', volumes=volumes)
  </code></pre>
  
  <p>And it prints :</p>
  
  <pre><code>Starting with UID: 0 and HOME: /src\n0\n'
  </code></pre>
  
  <p>Which means <code>data</code> is mounted, but empty. What am I doing wrong ?</p>