message: Ignore empty rustflags
diff: @@ -599,7 +599,10 @@ fn env_args(
  // First try CARG_ENCODED_RUSTFLAGS from the environment.
  // Prefer this over RUSTFLAGS since it's less prone to encoding errors.
  if let Ok(a) = env::var(format!("CARGO_ENCODED_{}", name)) {
  - let args = a.split('\x1f').map(str::to_string);
  + let args = a
  + .split('\x1f')
  + .filter(|s| !s.is_empty())
  + .map(str::to_string);
  return Ok(args.collect());
  }
  