title: How to merge branch and retain the authorship
body: <p>let's say that my colleage John has created a branch called 'john'. It has 10 committs by John. When it comes to merging back to master they ask me to do merging.</p>
  
  <p>This is what I do</p>
  
  <pre><code>git checkout -b john origin/john
  git rebase master
  git checkout master
  git merge john --squashed
  git add .
  git commit -m 'merged branch john'
  </code></pre>
  
  <p>However now what happens is that it is my id against the merged commit. And later people come asking me why did I change certain part of code.</p>
  
  <p>How do I collapse all the comitts in john branch into one commit such that John is the author. I guess git commit interactive can help but could not quite understand.</p>