title: Git reverts and cherry picks
body: <p>I'm puzzled by something, here's a summary.</p>
  
  <p>Our repo has a master branch and a d2l_phase_4 branch. Since the d2l_phase_4 branch was created several new commits have been added to master.</p>
  
  <p>Today someone incorrectly merged a pull request into master of a commit that should have been targeting the d2l_phase_4 branch.</p>
  
  <p>Therefore I did this:</p>
  
  <ol>
  <li>Reverted the commit and pushed to fork/master</li>
  <li>Made a pull request to the main repo/master.</li>
  <li>Merged that pull request.</li>
  </ol>
  
  <p>At this point we've safely undone the effect of the commit on our master branch.</p>
  
  <p>Then I did this:</p>
  
  <ol>
  <li>Checked out d2l_phase_4 branch</li>
  <li>Cherry picked the original commit from master.</li>
  <li>pushed to fork/d2l_phase_4</li>
  <li>Made a pull request targeting the main repo/d2l_phase_4</li>
  <li>Merged this pull request</li>
  </ol>
  
  <p>At this point the d2l_phase_4 branch has the desired changes from the original commit, so far so good.</p>
  
  <p>Finally I wanted to bring the d2l_phase_4 branch up to date with all the other stuff on master since the d2l_phase_4 branch was created. So again on the d2l_phase_4 branch I merged in from master and that created a new merge commit.</p>
  
  <p>I then push this updated d2l_phase_4 branch to my fork/d2l_phase_4 and finally created a pull request targeting the main repo/d2l_phase_4 and then merged that PR.</p>
  
  <p>However - it dawned on me that Id now merged in the earlier revert from the master branch and so must have nullified the commit that I'd earlier cherry picked!</p>
  
  <p>However when examining the state of files on the d2l_phase_4 there's no trace of the revert that was merged in from master - this is exactly what I want - but I do not understand.</p>
  
  <p>Why was my cherry picked commit on d2l_phase_4 not nullified by the revert that was merged in from master? I'd expected that I'd need to revert my revert on the d2l_phase_4 branch but when I attempted this git seemed to tell me there was nothing to revert...</p>
  
  <p>If I look at the histor one of the files involved, on the d2l_phase_4 branch then I see no trace of the revert or anything, all I can see if the cherry picked commit that I did.</p>