title: How to specify in the pipfile package from custom git branch using pipfile?
body: <p>It is possible to specify in <code>Pipfile</code> packages from custom Git repository.
  But I cannot find a comprehensive documentation on how to specify the concrete branch or a commit to be used for installation.</p>
  
  <p>Is there a complete reference on how to use Git URLs for python packages in the <code>Pipfile</code> that are supported by the <a href="https://pipenv.kennethreitz.org/" rel="noreferrer"><code>pipenv</code></a> for specifying custom branches, versions or commits?</p>
  
  <p>It would be really nice to have it with equivalent <code>pipenv</code> command line arguments.</p>