title: git filter-branch: options not supported in --stdin mode
body: <p>I'm trying to rename some commit messages using <code>git filter-branch --msg-filter</code> in windows cmd like this:</p>
  
  <pre><code>git filter-branch --msg-filter "python my_editing_script.py" -- --first-parent --no-merges 37827a6c7a65f8e878e..my_branch_name
  </code></pre>
  
  <p>The <code>my_editing_script.py</code> reads old messages from <code>stdin</code> and outputs new ones to <code>stdout</code>.</p>
  
  <p>But I get</p>
  
  <pre><code>fatal: options not supported in --stdin mode
  Could not get the commits
  </code></pre>
  
  <p>What am I doing wrong?</p>