title: installing cPickle with python 3.5
body: <p>This might be silly but I am unable to install <code>cPickle</code> with python 3.5 docker image</p>
  
  <p><strong>Dockerfile</strong></p>
  
  <pre><code>FROM python:3.5-onbuild
  </code></pre>
  
  <p><strong>requirements.txt</strong></p>
  
  <pre><code>cpickle
  </code></pre>
  
  <p>When I try to build the image</p>
  
  <pre><code>$ docker build -t sample .
  Sending build context to Docker daemon 3.072 kB
  Step 1 : FROM python:3.5-onbuild
  # Executing 3 build triggers...
  Step 1 : COPY requirements.txt /usr/src/app/
  Step 1 : RUN pip install --no-cache-dir -r requirements.txt
   ---&gt; Running in 016c35a032ee
  Collecting cpickle (from -r requirements.txt (line 1))
    Could not find a version that satisfies the requirement cpickle (from -r requirements.txt (line 1)) (from versions: )
  No matching distribution found for cpickle (from -r requirements.txt (line 1))
  You are using pip version 7.1.2, however version 8.1.1 is available.
  You should consider upgrading via the 'pip install --upgrade pip' command.
  The command '/bin/sh -c pip install --no-cache-dir -r requirements.txt' returned a non-zero code: 1
  </code></pre>