bug#22479: 25.0.50; isearch and query-replace histories do not remember if we were looking for symbols

[Dima Kogan <dima@secretsauce.net>]

Hi. It is possible to look for a symbol, and for this information to be
lost when repeating a search. For instance, say I have this buffer:

=======
a b c
ab bc
=======

1. I put the point on the first 'a'

2. M-s . (search for symbol at point). This find a symbol 'a', so the
   'a' in 'ab' doesn't match

3. C-g (quit the search)

4. C-s C-s (repeat previous search). Here emacs remembers we looked for
   'a', but not that it was a symbol, so it finds the 'a' in 'ab' even
   though it should not



A similar sequence is possible with query-replace:

1. Point on 'a'

2. M-s .

3. C-M-%, 'asdf' to replace the symbol 'a' with 'asdf'

4. C-g (quit before replacing anything)

5. C-M-% (repeat last replacement. The symbol-ness of 'a' was forgotten)


The simplest way to fix this would probably be to treat these as regex
searches wrapped in \_<...\_>. The downside is that to access the
history we'd have to do C-M-s C-M-s instead of C-s C-s, but maybe that
is ok. Thoughts?