func (s *Server) getPatch(org, repo, targetBranch string, num int) (string, error) {
	patch, err := s.ghc.GetPullRequestPatch(org, repo, num)
	if err != nil {
		return "", err
	}
	localPath := fmt.Sprintf("/tmp/%s_%s_%d_%s.patch", org, repo, num, normalize(targetBranch))
	out, err := os.Create(localPath)
	if err != nil {
		return "", err
	}
	defer out.Close()
	if _, err := io.Copy(out, bytes.NewBuffer(patch)); err != nil {
		return "", err
	}
	return localPath, nil
}
func (s *Server) getPatch(org, repo, targetBranch string, num int) (string, error) {
	patch, err := s.ghc.GetPullRequestPatch(org, repo, num)
	if err != nil {
		return "", err
	}
	localPath := fmt.Sprintf("/tmp/%s_%s_%d_%s.patch", org, repo, num, normalize(targetBranch))
	out, err := os.Create(localPath)
	if err != nil {
		return "", err
	}
	defer out.Close()
	if _, err := io.Copy(out, bytes.NewBuffer(patch)); err != nil {
		return "", err
	}
	return localPath, nil
}
// getPatch gets the patch for the provided PR and creates a local
// copy of it. It returns its location in the filesystem and any
// encountered error.