bug#9918: 24.0.90; lazy-highlighting in Info mode

[Dani Moncayo]

> But Info Isearch sets `isearch-error' to "initial node", so
> `isearch-lazy-highlight-new-loop' doesn't start lazy-highlighting.
> It seems with the error "initial node", it's still possible to
> lazy-highlight other matches.  So it's not a normal error,
> and we can make an exception for this type of "error".
> This will work with the following patch:
>
> [...]
>
> But it's not good to hardcode it, so perhaps we should introduce
> a special property for errors that are not quite an error,
> and set it just for "initial node".

Indeed.

IIUC, "initial node" just inform the user that the current search is
failing inside this node (where the search started), but this should
not be considered an error (like "incomplete input" or "No previous
search string"), because "initial node", unlike "incomplete input",
does not deactivate the current Isearch.

So, I think that maybe TRT would be to move the "inital node" message
to the Isearch prompt, so that such prompt would be "Failing I-search
(initial node): ".

BTW: while looking for sentences that set the value of `isearch-error'
inside lisp/isearch.el, I've noticed that some errors begins with an
uppercase letter ("No previous search string") and others don't
("incomplete input").  This should be fixed to make it consistent for
all error messages.

-- 
Dani Moncayo