title: Open pull request on a single commit
body: <p>I have a branch with 3 or 4 commits pushed to it on GitHub.  I would like to open a pull request to our master branch involving only one of those commits.  However, the GitHub interface appears to require a new PR to include all those commits.</p>
  
  <p>Is it possible to open a new pull request using a subset of my branch's commits?</p>