title: Pipenv: Specify local version of python package in pipfile
body: <p>I have a pipfile that looks something like this:</p>
  
  <pre><code>[packages]
  pyarrow = "*"
  tensorflow = "==1.8.0"
  h5py = "*"
  </code></pre>
  
  <p>I have another package, <code>xyz</code>, that exists in a github repo.  I've cloned that repo, made some edits to it, and now want to include the <em>edited</em> version in my pipfile.  If it helps, I also have the modified version of <code>xyz</code> in a branch on Github.</p>
  
  <p>How might I do this?</p>