title: Update Git branches from master
body: <p>I'm new to Git, and now I'm in this situation:</p>
  
  <ul>
  <li>I have four branches (master, b1, b2, and b3).</li>
  <li>After I worked on b1-b3, I realized I have something to change on branch master that should be in all other branches.</li>
  <li>I changed what I needed in <code>master</code> and... here is my problem:</li>
  </ul>
  
  <p>How do I update all other branches with <code>master</code> branch code?</p>