message: Keep the unused enum variant visible in the code to prevent its re-use in the future
diff: @@ -18,6 +18,11 @@ pub enum ExitCode {
  /// The process should exit with `101`, equivalent to panicking. The launcher should not
  /// restart the node.
  Abort = 101,
  + /// The process should exit with `102`. It used to be an indication to the launcher
  + /// that it should proceed to run the previous installed version of `casper-node`.
  + /// It is no longer used, but we keep it here to avoid it being reassigned to other features.
  + #[doc(hidden)]
  + DowngradeVersion = 102,
  /// The exit code Rust uses by default when interrupted via an `INT` signal.
  SigInt = SIGNAL_OFFSET + SIGINT as u8,
  /// The exit code Rust uses by default when interrupted via a `QUIT` signal.
  