src/Pure/Tools/build_history.scala

--- a/src/Pure/Tools/build_history.scala	Mon Oct 03 17:23:33 2016 +0200
+++ b/src/Pure/Tools/build_history.scala	Mon Oct 03 18:54:59 2016 +0200
@@ -12,8 +12,6 @@
 
 object Build_History
 {
-  val rev0 = "0cebcbeac4c7"  // wenzelm 29-Aug-2012: provide polyml-5.4.1 as regular component
-
   def apply(hg: Mercurial.Repository, rev: String = "",
     isabelle_identifier: String = "build_history"): Build_History =
       new Build_History(hg, rev, isabelle_identifier)