Re: occur-hook changing the current buffer

[Richard M. Stallman]

    Now, I can easily change my function to do the right thing, but I
    still feel that `occur-1' should be fixed by using
    `save-current-buffer' around the call to "(run-hooks 'occur-hook). The
    rationale being that setting the modified flag to nil on the wrong
    buffer can lead to data loss.

You may as well install the patch.  It can't hurt, and it can
prevent confusion.