bug#15166: 24.3.50; Isearch for an octal code

[Drew Adams <drew.adams@oracle.com>]

> > What doesn't work?
> 
> The docstring of `isearch-forward-regexp' says "To search
> for a literal space and nothing else, enter C-q SPC."
> The users might expect it to work the same way regardless of mode,
> but it doesn't search for a literal space in non-regexp mode.

Got it. Yes, that text is now out of date.

It never should have said that C-q SPC affects what is
searched for, in any case.  It should only have said (and
can say now) that C-q SPC, as usual, appends a SPC char to
the search string.

What Isearch does with the text you put in the search string
is another matter.  But C-q SPC still works - it does what it
is supposed to do.  It is Isearch that is more complicated
now, and not necessarily intuitive.  But that cannot be blamed
on C-q.  ;-)