src/Pure/Admin/build_release.scala

   val ISABELLE_TAGS: Path = Path.explode("etc/ISABELLE_TAGS")
   val ISABELLE_IDENTIFIER: Path = Path.explode("etc/ISABELLE_IDENTIFIER")
 
   object Release_Archive {
     def make(bytes: Bytes, rename: String = ""): Release_Archive = {
-      Isabelle_System.with_tmp_dir("tmp")(dir =>
+      Isabelle_System.with_tmp_dir("build_release")(dir =>
         Isabelle_System.with_tmp_file("archive", ext = "tar.gz") { archive_path =>
           val isabelle_dir = Isabelle_System.make_directory(dir + ISABELLE)
 
           Bytes.write(archive_path, bytes)
           execute_tar(isabelle_dir, "-xzf " + File.bash_path(archive_path), strip = 1)