message: Maybe like this?
diff: @@ -74,7 +74,7 @@ if len(existing_duckdb_dir) == 0:
  (source_list, include_list, original_sources, githash) = package_build.build_package(os.path.join(script_path, 'duckdb'))
  - duckdb_sources = [package_build.get_relative_path(script_path, x) for x in source_list]
  + duckdb_sources = [os.path.sep.join(package_build.get_relative_path(script_path, x).split('/')) for x in source_list]
  duckdb_sources.sort()
  original_sources = [os.path.join('duckdb', x) for x in original_sources]
  