title: Switch to another branch without changing the workspace files
body: <p>I cloned a git repository from GitHub, made some changes and some commits; I made quite a lot and all are quite dirty, so they're not suitable for a pull request. Now I created the branch <code>cleanchanges</code> from <code>origin/master</code>, so it's clean, and I want to commit my changes there as one commit with a nice commit comment.</p>
  
  <p>When I am on the local master, I want to switch to my <code>cleanchanges</code> but without changing the files. And then I'm able to commit.</p>
  
  <p>How can I switch branches without changing files?</p>
  
  <p>I want to make it clear: I have all the changes committed in the local <code>master</code>. There are no uncommitted changes.</p>