title: How to view the net contribution of one git branch to another over the entire lifetime of the contributing branch
body: <p>We have a central MASTER branch and multiple individual task branches, and our lifecycle is something like as follows:</p>
  
  <blockquote>
    <ol>
    <li>create individual task branch A from MASTER </li>
    <li>do work on A and complete task</li>
    <li>merge A back into MASTER</li>
    <li>...if testing identifies additional changes required in A, then merge latest MASTER into A (to bring A back up to speed with tasks
    B,C,.... that may have been merged into MASTER in the interim)</li>
    <li>fix the issues in branch A</li>
    <li>merge A back into MASTER</li>
    <li>(repeat 4 => 6 until A work signed off)</li>
    </ol>
  </blockquote>
  
  <p>The above is fine but what we need to do after step 7 is identify (via some kind of GIT diff):</p>
  
  <p>The net changes - after completion of the above lifecycle - that A has introduced into MASTER.</p>
  
  <p>So effectively we are looking for a one-way diff A => MASTER showing the net change introduced by A into MASTER after multiple merges have taken place bidirectionally between the the two branches.</p>
  
  <p>Would greatly appreciate any input I can get on this - thanks!</p>