title: How to add new folder to git branch without adding it to master
body: <p>How does one add a new folder to a branch in git without having that folder show up in the master branch?</p>
  
  <pre><code>e.g. 
  git branch myNewBranch
  git checkout myNewBranch
  mkdir foo
  
  git checkout master
  ls
  </code></pre>
  
  <p>the myNewBranch directory is also added to master</p>