diff --git a/Admin/components/main b/Admin/components/main
--- a/Admin/components/main
+++ b/Admin/components/main
@@ -1,31 +1,31 @@
 #main components for repository clones or release bundles
 gnu-utils-20210414
 bash_process-1.2.4-2
 bib2xhtml-20190409
 csdp-6.1.1
 cvc4-1.8
 e-2.5-1
 flatlaf-1.2
 idea-icons-20210508
 isabelle_fonts-20210322
 isabelle_setup-20210630
 jdk-15.0.2+7
 jedit_build-20210510-1
 jfreechart-1.5.1
 jortho-1.0-2
 kodkodi-1.5.6-1
 nunchaku-0.5
 opam-2.0.7
 polyml-5.8.2
 postgresql-42.2.18
-scala-2.13.6
+scala-2.13.5
 smbc-0.4.1
 spass-3.8ds-2
 sqlite-jdbc-3.34.0
 ssh-java-20190323
 stack-2.5.1
 vampire-4.2.2
 verit-2020.10-rmx-1
 xz-java-1.8
 z3-4.4.0pre-3
 zipperposition-2.0-1
diff --git a/src/Pure/ROOT.scala b/src/Pure/ROOT.scala
--- a/src/Pure/ROOT.scala
+++ b/src/Pure/ROOT.scala
@@ -1,24 +1,23 @@
 /*  Title:      Pure/ROOT.scala
     Author:     Makarius
 
 Root of isabelle package.
 */
 
 package object isabelle
 {
   val ERROR = Exn.ERROR
   val error = Exn.error _
   def cat_error(msgs: String*): Nothing = Exn.cat_error(msgs:_*)
 
   def using[A <: AutoCloseable, B](a: A)(f: A => B): B = Library.using(a)(f)
   val space_explode = Library.space_explode _
   val split_lines = Library.split_lines _
   val cat_lines = Library.cat_lines _
   val terminate_lines = Library.terminate_lines _
   val quote = Library.quote _
   val commas = Library.commas _
   val commas_quote = Library.commas_quote _
   val proper_string = Library.proper_string _
   def proper_list[A](list: List[A]): Option[List[A]] = Library.proper_list(list)
 }
-