message: librustzcash: Correctly map sprout_path
diff: @@ -191,7 +191,7 @@ pub extern "system" fn librustzcash_init_zksnark_params(
  spend_hash,
  Path::new(&output_path),
  output_hash,
  - Path::new(&sprout_path),
  + sprout_path.as_ref().map(|p| Path::new(p)),
  sprout_hash,
  )
  }
  