title: Why does git say "Pull is not possible because you have unmerged files"?
body: <p>When I try to pull in my project directory in the terminal, I see the following error:</p>
  
  <pre><code>harsukh@harsukh-desktop:~/Sites/branch1$ git pull origin master
  U app/config/app.php
  U app/config/database.php
  U app/routes.php
  Pull is not possible because you have unmerged files.
  Please, fix them up in the work tree, and then use 'git add/rm &lt;file&gt;'
  as appropriate to mark resolution, or use 'git commit -a'.
  </code></pre>
  
  <p>Why does git say <code>"Pull is not possible because you have unmerged files"</code>, and how can I resolve it?</p>