title: Replacing dependency with custom forks using pip
body: <p>I am building an app that uses <code>photologue</code> and a few other packages that have <code>photologue</code> as a dependency (e.g., <code>cmsplugin-photologue</code>). However, I need to use a modified version of <code>photologue</code> hosted on github. All this will then be deployed on Heroku, which means that installations of dependencies is done solely through a <code>requirements.txt</code> file.</p>
  
  <p>In principle this is done quite easily: I can just add the repository to the requirements file  as described <a href="https://devcenter.heroku.com/articles/python-pip#git-backed-distributions" rel="nofollow">here</a> and it will be installed. The problem is that the original <code>photologue</code> is installed too and ends up the one being used.</p>
  
  <p>So the general question is: Using <code>pip</code>, how can I replace an application that is a dependency of several apps with my own version of that application?</p>