src/Pure/System/invoke_scala.scala

   {
     val NULL = Value("0")
     val OK = Value("1")
     val ERROR = Value("2")
     val FAIL = Value("3")
+    val INTERRUPT = Value("4")
   }
 
   def method(name: String, arg: String): (Tag.Value, String) =
     Exn.capture { get_method(name) } match {
       case Exn.Res(f) =>
         Exn.capture { f(arg) } match {
           case Exn.Res(null) => (Tag.NULL, "")
           case Exn.Res(res) => (Tag.OK, res)
+          case Exn.Exn(_: InterruptedException) => (Tag.INTERRUPT, "")
           case Exn.Exn(e) => (Tag.ERROR, Exn.message(e))
         }
       case Exn.Exn(e) => (Tag.FAIL, Exn.message(e))
     }
 }