diff -r b5fb99b985b4 -r 18d80cd51823 src/Pure/Tools/build.scala
--- a/src/Pure/Tools/build.scala	Tue May 25 23:37:32 2021 +0200
+++ b/src/Pure/Tools/build.scala	Tue May 25 23:58:49 2021 +0200
@@ -535,7 +535,6 @@
 
     var base_sessions: List[String] = Nil
     var select_dirs: List[Path] = Nil
-    var log: Logger = No_Logger
     var numa_shuffling = false
     var presentation = Presentation.Context.none
     var requirements = false