diff -r 4c32c5e75eca -r 84bfb2162dd2 src/Pure/Tools/isabelle_system.scala --- a/src/Pure/Tools/isabelle_system.scala Sat Aug 23 17:55:26 2008 +0200 +++ b/src/Pure/Tools/isabelle_system.scala Sat Aug 23 17:55:27 2008 +0200 @@ -20,7 +20,9 @@ if (value != null) value else "" } - class BadVariable(val name: String) extends Exception + class BadVariable(val name: String) extends Exception { + override def toString = "BadVariable: " + name + } def getenv_strict(name: String) = { val value = getenv(name)