message: Fixup some minor review comments
diff: @@ -73,19 +73,20 @@ impl Invocation {
  self.program = cmd.get_program()
  .to_str()
  .ok_or_else(|| format_err!("unicode program string required"))?
  - .to_string()
  - .clone();
  + .to_string();
  self.cwd = Some(cmd.get_cwd().unwrap().to_path_buf());
  for arg in cmd.get_args().iter() {
  self.args.push(
  arg.to_str()
  .ok_or_else(|| format_err!("unicode argument string required"))?
  - .to_string()
  - .clone(),
  + .to_string(),
  );
  }
  - for var in cmd.get_envs().keys() {
  - let value = cmd.get_env(var).unwrap_or_default();
  + for (var, value) in cmd.get_envs() {
  + let value = match value {
  + Some(s) => s,
  + None => continue,
  + };
  self.env.insert(
  var.clone(),
  value
  