bug#141: Process sentinel not called in batch mode

[Richard M Stallman]

    > This problem occurs because wait_reading_process_output only calls
    > status_notify when given a nonzero DO_DISPLAY argument (process.c:4451).
    > Although wait_reading_process_output is called from many places in
    > Emacs, it is given a nonzero DO_DISPLAY argument only during
    > kbd_buffer_get_event.  But that function is never called in batch mode.

    Does anyone know why we test do_display there?

I think the idea is, if you are going to update the display, it is
good to display the fact that a process has terminated.

I don't claim this implies the code should not be changed.