src/Pure/System/scala.scala

--- a/src/Pure/System/scala.scala	Sun May 24 19:45:42 2020 +0200
+++ b/src/Pure/System/scala.scala	Sun May 24 20:35:24 2020 +0200
@@ -31,7 +31,7 @@
 
       val class_path =
         for {
-          prop <- List("scala.boot.class.path", "java.class.path")
+          prop <- List("isabelle.scala.classpath", "java.class.path")
           path = System.getProperty(prop, "") if path != "\"\""
           elem <- space_explode(JFile.pathSeparatorChar, path)
         } yield elem