title: Customize colors for __git_ps1 with GIT_PS1_SHOWCOLORHINTS
body: <h2>What I have tried</h2>
  
  <p>I have updated my prompt to include the branch name using <code>__git_ps1</code>. In addition, I set <code>GIT_PS1_SHOWCOLORHINTS</code>.</p>
  
  <h2>The problem</h2>
  
  <p>The prompt appears correctly. However, the branch color is always green. I expected a dirty branch to be red.</p>
  
  <p>The docs state:</p>
  
  <blockquote>
    <p>The colors are based on the colored output of "git status -sb"</p>
  </blockquote>
  
  <p>I found and reviewed <a href="https://stackoverflow.com/questions/12795790/how-to-colorize-git-status-output">How to colorize git-status output?</a> But I'm not sure what options I'd need to change...</p>
  
  <h2>The question</h2>
  
  <p>Is it possible to change the branch color to be green for a <em>clean</em> branch and red for a <em>dirty</em> branch? If so, how?</p>