diff -r 26cd26aaf108 -r a8ff6e4ee661 src/Pure/Tools/build.scala
--- a/src/Pure/Tools/build.scala	Tue May 18 22:02:21 2021 +0200
+++ b/src/Pure/Tools/build.scala	Wed May 19 10:41:28 2021 +0200
@@ -576,7 +576,7 @@
 
   Build and manage Isabelle sessions, depending on implicit settings:
 
-""" + Library.prefix_lines("  ",  Build_Log.Settings.show()) + "\n",
+""" + Library.indent_lines(2,  Build_Log.Settings.show()) + "\n",
       "B:" -> (arg => base_sessions = base_sessions ::: List(arg)),
       "D:" -> (arg => select_dirs = select_dirs ::: List(Path.explode(arg))),
       "N" -> (_ => numa_shuffling = true),