src/Pure/Tools/build.scala

--- a/src/Pure/Tools/build.scala	Tue Oct 31 16:42:20 2017 +0100
+++ b/src/Pure/Tools/build.scala	Tue Oct 31 17:03:57 2017 +0100
@@ -380,7 +380,8 @@
 
     /* session selection and dependencies */
 
-    val full_sessions = Sessions.load(build_options, dirs, select_dirs)
+    val full_sessions =
+      Sessions.load(build_options, dirs = dirs, select_dirs = select_dirs)
 
     def sources_stamp(deps: Sessions.Deps, name: String): String =
     {