title: How can I move multiple directories in a Git?
body: <p>There is a Git repository like this. </p>
  
  <pre><code>   repo/
        A1/
          B1/
            C1/
        A2/
          B2/
            C2/
  </code></pre>
  
  <p>I would like to have one like this.</p>
  
  <pre><code>   repo/
        C1/
        C2/
  </code></pre>
  
  <p>I don't need A1, B1, A2, B2 directories any more.</p>
  
  <pre><code>$ git filter-branch --tree-filter 'mv A1/B1/C1 .' HEAD
  Rewrite xxxx(1/206)mv: cannot stat 'A1/B1/C1': No such file or directory
  tree filter failed: mv A1/B1/C1 .
  </code></pre>
  
  <p>Any ideas?</p>