title: How to rebase many branches (with the same base commit) at once?
body: <p>I have a master branch in my project, that I use to pull changes from other people. From that, I usually have several topic branches on which I'm currently working.</p>
  <p>My question is: Is there a way for me to pull new changes into my master and then rebase ALL of my topic branches onto that at once?</p>
  <p>This is the situation:</p>
  <pre><code>        D--E topic1
         /
  A--B--C master
         \
          F--G topic2
  </code></pre>
  <p>And I want to accomplish this with one single command (H came from upstream) :</p>
  <pre>
                 D'--E' topic1
                /
      A--B--C--H master
                \
                 F'--G' topic2
  </pre>
  <p>Now, I know I can accomplish this by rebasing topic1 and topic2 onto master, and I could even write a script to automate this. But what if I have several other branches, create new ones and delete others frequently and I receive upstream changes all the time?</p>
  <p>This operation (several rebases), when done by hand, is both tiring and error-prone.</p>
  <p>Is there an easier way?</p>