title: Heroku can't find pip (very strange)
body: <p>When I push to master, this happened:</p>
  
  <pre><code>Counting objects: 1, done.
  Writing objects: 100% (1/1), 186 bytes, done.
  Total 1 (delta 0), reused 0 (delta 0)
  
  -----&gt; Fetching custom git buildpack... done
  -----&gt; Python app detected
  -----&gt; Preparing Python runtime (python-2.7.3)
  -----&gt; Installing Distribute (0.6.35)
  -----&gt; Installing Pip (1.3.1)
  -----&gt; Installing dependencies using Pip (1.3.1)
  /tmp/buildpack_12iaablbmqzbb/bin/compile: line 164: /app/.heroku/python/bin/pip: No such file or directory
   !     Heroku push rejected, failed to compile Python app
  
  To git@heroku.com:xxxxxxxxxx.git
   ! [remote rejected] master -&gt; master (pre-receive hook declined)
  </code></pre>
  
  <p>To be clear, I specified build pack, because heroku wrongly detected my python app as ruby app due to the existence of Gemfile.</p>
  
  <p>This is the config I pulled from <code>heroku config</code></p>
  
  <pre><code>BUILDPACK_URL: https://github.com/heroku/heroku-buildpack-python
  </code></pre>
  
  <p>But this fail to compile my app, how can I really solve this?</p>
  
  <p>Thanks.</p>