title: Git editor error
body: <p>I get following error message, when I try to run <code>git rebase -i</code> for squashing my commit:</p>
  
  <pre><code>/usr/libexec/git-core/git-sh-setup: line 112: mate: command not found
  </code></pre>
  
  <p>How does git look for the editor?
  From the <code>git-sh-setup</code> file, I can only see this method:</p>
  
  <pre><code>git_editor() {                                                                       
      if test -z "${GIT_EDITOR:+set}" 
      then                                                                             
          GIT_EDITOR="$(git var GIT_EDITOR)" || return $?                              
      fi                                                                               
      eval "$GIT_EDITOR" '"$@"'                                                                                                                                                    
  } 
  </code></pre>