title: Rename branches in git bare repository
body: <p>Is it ok to rename branches in bare repository at packed-refs file?</p>
  
  <p>I want to rename it from:</p>
  
  <pre><code># pack-refs with: peeled fully-peeled 
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa refs/heads/master
  bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb refs/heads/new
  </code></pre>
  
  <p>to:</p>
  
  <pre><code># pack-refs with: peeled fully-peeled 
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa refs/heads/old
  bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb refs/heads/master
  </code></pre>