message: Fix a clippy lint
diff: @@ -92,7 +92,7 @@ pub fn package(ws: &Workspace, opts: &PackageOpts) -> CargoResult<Option<FileLoc
  .shell()
  .status("Packaging", pkg.package_id().to_string())?;
  dst.file().set_len(0)?;
  - tar(ws, &src_files, vcs_info, dst.file(), &filename)
  + tar(ws, &src_files, vcs_info.as_ref(), dst.file(), &filename)
  .chain_err(|| format_err!("failed to prepare local package for uploading"))?;
  if opts.verify {
  dst.seek(SeekFrom::Start(0))?;
  @@ -269,7 +269,7 @@ fn check_vcs_file_collision(pkg: &Package, src_files: &[PathBuf]) -> CargoResult
  fn tar(
  ws: &Workspace,
  src_files: &[PathBuf],
  - vcs_info: Option<serde_json::Value>,
  + vcs_info: Option<&serde_json::Value>,
  dst: &File,
  filename: &str
  ) -> CargoResult<()> {
  