code: func gitVersion() string {
  	cmd := exec.Command("git", "rev-list", "--max-count=1", "--pretty=format:'%ad-%h'",
  		"--date=short", "--abbrev=10", "HEAD")
  	cmd.Dir = camliDir
  	out, err := cmd.Output()
  	if err != nil {
  		log.Fatalf("Error running git rev-list in %s: %v", camliDir, err)
  	}
  	v := strings.TrimSpace(string(out))
  	if m := gitVersionRx.FindStringSubmatch(v); m != nil {
  		v = m[0]
  	} else {
  		panic("Failed to find git version in " + v)
  	}
  	cmd = exec.Command("git", "diff", "--exit-code")
  	cmd.Dir = camliDir
  	if err := cmd.Run(); err != nil {
  		v += "+"
  	}
  	return v
  }
docs: // gitVersion returns the git version of the git repo at camRoot as a
  // string of the form "yyyy-mm-dd-xxxxxxx", with an optional trailing
  // '+' if there are any local uncommitted modifications to the tree.