message: fix add-essential-files command
diff: @@ -219,6 +219,7 @@ impl RustwideBuilder {
  }
  pub fn add_essential_files(&mut self) -> Result<()> {
  + self.rustc_version = self.detect_rustc_version()?;
  let rustc_version = parse_rustc_version(&self.rustc_version)?;
  info!("building a dummy crate to get essential files");
  