bug#7718: 23.2.91; Info-isearch-search fails isearch

[Juri Linkov]

>> Info-isearch-search does not implement the noerror arg because it just 
>> passes it
>> unchanged to Info-search.  Do you mean Info-search should implement noerror 
>> for
>> some non-interactive uses?  What it should do when noerror is non-nil?
>
> That's what I meant. Info-search doesn't implement noerror. I think it
> should be like the default isearch search functions:
> re-/search-forward/backward: Optional argument, if t, means if fail just
> return nil (no error).

But the whole logic of Isearch using Info-search is built on the
assumption that Info-search ignores the noerror arg (that is usually t).
This allow Isearch to fail in the initial Info node
and to continue searching through other nodes without failing.