title: automerge modification in the same file
body: <p>I have new repository called myrepo and I have master branch with two previous commits, the first commit with a file1.txt and second commit with a file2.txt.</p>
  
  <ul>
  <li><p>After the second commit, created a new branch called file2Split.</p></li>
  <li><p>After that I realize that file2.txt is too big, how I want to split<br>
  its content by creating a new file2a.txt, and then commit the<br>
  modifications.</p></li>
  <li><p>myquestion is how can I automerge modifications in the same files.</p></li>
  </ul>