message: Tidy up subcommand logic slightly
diff: @@ -44,10 +44,9 @@ pub fn main(config: &mut Config) -> CliResult {
  (ContextKind::InvalidSubcommand, &ContextValue::String(ref cmd)) => {
  Some(cmd)
  }
  - (ContextKind::InvalidSubcommand, _) => unreachable!(),
  _ => None,
  })
  - .unwrap();
  + .expect("UnrecognizedSubcommand implies the presence of InvalidSubcommand");
  return super::execute_external_subcommand(config, &cmd, &[&cmd, "--help"])
  .map_err(|_| e.into());
  } else {
  