src/Pure/Admin/build_release.scala

     else {
       progress.echo_warning("Preparing release " + context.dist_name + " ...")
 
       Isabelle_System.new_directory(context.dist_dir)
 
-      hg.archive(context.isabelle_dir.expand.implode, rev = id)
+      hg.archive(File.standard_path(context.isabelle_dir), rev = id)
 
       for (name <- List(".hg_archival.txt", ".hgtags", ".hgignore", "README_REPOSITORY")) {
         (context.isabelle_dir + Path.explode(name)).file.delete
       }