title: Make old git branches invisible without making them unreachable?
body: <p>Is there a way to make a git branch cease to show up when you type "git branch", but still remain reachable in the history, i.e. via gitk?  I have many old branches that I want to get out of my sight, but I see no reason to delete history even of development dead-ends in a world with terabyte hard disks. </p>
  
  <p>Tags might be close to what I'm looking for, but I don't want to have to name my dead ends beyond their commit message.  Furthermore, I want reserve tags for especially good points in the mainline development history.</p>