code: func allAuthors() map[string]string {
  	args := append([]string{"log", "--format=%H %ae %an"})
  	cmd := exec.Command("git", args...)
  	bs, err := cmd.Output()
  	if err != nil {
  		log.Fatal("git:", err)
  	}
  
  	names := make(map[string]string)
  	for _, line := range bytes.Split(bs, []byte{'\n'}) {
  		fields := strings.SplitN(string(line), " ", 3)
  		if len(fields) != 3 {
  			continue
  		}
  		hash, email, name := fields[0], fields[1], fields[2]
  
  		if excludeCommits.has(hash) {
  			continue
  		}
  
  		if names[email] == "" {
  			names[email] = name
  		}
  	}
  
  	return names
  }
docs: // allAuthors returns the set of authors in the git commit log, except those
  // in excluded commits.