title: pip cannot find package from local pypi (jfrog artifactory)
body: <p>We have a local pypi in which we put some python packages. However, pip is unable to install the package. </p>
  
  <p>pip search will find the package:</p>
  
  <pre><code>$ pip search --index=http://artifactory.ours.com/api/pypi/pypi-local/simple hello        
  hello     - UNKNOWN
  </code></pre>
  
  <p>But pip install gives the following:</p>
  
  <pre><code>pip install --pre -r requirements.txt --trusted-host=artifactory.ours.com
  </code></pre>
  
  <blockquote>
    <p>Collecting hello (from -r requirements.txt (line 4))   Could not
    find a version that satisfies the requirement hello (from -r
    requirements.txt (line 4)) (from versions: ) No matching distribution
    found for hello (from -r requirements.txt (line 4))</p>
  </blockquote>
  
  <p>and here is the requirements.txt:</p>
  
  <pre><code># requirements.txt
  --allow-all-external
  --extra-index-url http://artifactory.ours.com/artifactory/api/pypi/pypi-local/simple
  
  hello
  </code></pre>