title: git rebase could not execute editor
body: <p>I'm attempting to squash some git commits using rebase. When I run this:</p>
  
  <pre><code>git rebase -i HEAD
  </code></pre>
  
  <p>I get this error:</p>
  
  <pre><code>/usr/lib/git-core/git-rebase: 1: eval: /usr/bin/mate: not found
  Could not execute editor
  </code></pre>
  
  <p>I've attempted to change the git config editor variable but I haven't gotten it to work. Right now my config file shows the following:</p>
  
  <pre><code>[core]
      editor = /usr/bin/vim
  </code></pre>
  
  <p>I'm running Ubuntu 13.04</p>
  
  <p>Any ideas?</p>