title: git show old version of file in editor
body: <p>I figured out I can show old versions of a file using 'git log filename' to show the commits, and then use 'git show commit-id:filename' for the old version. But it just puts it in less.</p>
  
  <p>I would like to be able to view this in emacs, so I can navigate as I'm used to and so that there is syntax highlighting. I found out I can't set the git core.pager to emacs since emacs cannot read from stdin.</p>
  
  <p>Does anyone know how I could do this? Or do you have another good way of checking old versions of files?</p>