message: update warning message when retrying toolchain update
diff: @@ -229,7 +229,11 @@ fn retry<T>(mut f: impl FnMut() -> Result<T>) -> Result<T> {
  if attempt > MAX_ATTEMPTS {
  return Err(err);
  } else {
  - log::warn!("got error {:?} on attempt {}, will try again", err, attempt);
  + log::warn!(
  + "got error on attempt {}, will try again:\n{:?}",
  + attempt,
  + err
  + );
  }
  }
  }
  