proper session dirs;

--- a/src/Pure/Tools/process_theories.scala	Mon Aug 11 20:29:04 2025 +0200
+++ b/src/Pure/Tools/process_theories.scala	Mon Aug 11 20:34:38 2025 +0200
@@ -123,7 +123,7 @@
         }
       }
 
-      Build.build(options, private_dir = Some(private_dir), progress = progress,
+      Build.build(options, private_dir = Some(private_dir), dirs = dirs, progress = progress,
         infos = List(session_info), selection = Sessions.Selection.session(session_name),
         session_setup = session_setup)
     }