src/Pure/General/ssh.scala

 
     def close(): Unit = channel.disconnect
 
     val exit_status: Future[Int] =
       Future.thread("ssh_wait") {
-        while (!channel.isClosed) exec_wait_delay.sleep
+        while (!channel.isClosed) exec_wait_delay.sleep()
         channel.getExitStatus
       }
 
     val stdin: OutputStream = channel.getOutputStream
     val stdout: InputStream = channel.getInputStream

           if (c == 10) line_flush()
           else if (channel.isClosed) {
             if (line_buffer.size > 0) line_flush()
             finished = true
           }
-          else exec_wait_delay.sleep
+          else exec_wait_delay.sleep()
         }
 
         result.toList
       }