diff -r 2e352f63d15f -r 40624a9e94c4 src/Pure/System/isabelle_process.scala
--- a/src/Pure/System/isabelle_process.scala	Tue Mar 08 20:24:41 2016 +0100
+++ b/src/Pure/System/isabelle_process.scala	Tue Mar 08 20:33:34 2016 +0100
@@ -21,7 +21,7 @@
     val process =
       try {
         ML_Process(options, heap = heap, args = args, modes = modes, secure = secure,
-          process_socket = channel.server_name)
+          channel = Some(channel))
       }
       catch { case exn @ ERROR(_) => channel.accepted(); throw exn }
     process.stdin.close