src/Pure/System/isabelle_system.scala

         val shell_prefix =
           if (Platform.is_windows) List(platform_root + "\\bin\\bash", "-l") else Nil
         val cmdline =
           shell_prefix ::: List(isabelle_home + "/bin/isabelle", "getenv", "-d", dump.toString)
         val (output, rc) =
-          Standard_System.process_output(Standard_System.raw_execute(env0, true, cmdline: _*))
+          Standard_System.process_output(Standard_System.raw_execute(null, env0, true, cmdline: _*))
         if (rc != 0) error(output)
 
         val entries =
           for (entry <- Source.fromFile(dump).mkString split "\0" if entry != "") yield {
             val i = entry.indexOf('=')

   def execute(redirect: Boolean, args: String*): Process =
   {
     val cmdline =
       if (Platform.is_windows) List(platform_root + "\\bin\\env.exe") ++ args
       else args
-    Standard_System.raw_execute(environment, redirect, cmdline: _*)
+    Standard_System.raw_execute(null, environment, redirect, cmdline: _*)
   }
 
 
   /* getenv */