Re: undo-information kept for *occur*

[Richard Stallman]

    ***************
    *** 739,744 ****
    --- 739,745 ----
        (use-local-map occur-mode-map)
        (setq major-mode 'occur-mode)
        (setq mode-name "Occur")
    +   (setq buffer-undo-list t) ; Don't record undo information.
        (set (make-local-variable 'revert-buffer-function) 
'occur-revert-function)
        (make-local-variable 'occur-revert-arguments)
        (add-hook 'change-major-mode-hook 'font-lock-defontify nil t)

This is not correct, because it seems to leave buffer-undo-list
permanently set to t.  That prevents undoing of changes made by hand
by the user.