title: Having a private branch of a public repo on GitHub?
body: <p>I have a public PHP project in a GitHub repo, which contains just one branch (master).</p>
  
  <p>I want to have a separate branch/fork that is private for me (I have paid for private GitHub repos). I would like to be able to merge changes from the private branch/fork to the public repo, and vice versa.</p>
  
  <p>With that in mind, here are my questions:</p>
  
  <ol>
  <li>Can I have a private branch on a public repo?</li>
  <li>Can I fork my own public repo into my own private branch/fork?</li>
  <li>If both of the above are possible, which is the best way forward? If neither, how should I proceed?</li>
  </ol>