bug#13467: 24.3.50; Problem with `advice' show-paren-function

[Drew Adams]

> >     (if (char-equal (char-syntax (char-before (point))) ?\))
> 
> What do you expect this do if called eg at point-min?
> Maybe fail with wrong-type-argument characterp nil?

E.g.,

(let ((matching-text nil)
      (cb            (char-before (point))))
  (when (and cb  (char-equal (char-syntax cb) ?\) ))
    (setq matching-text  (blink-matching-open)))
  (when matching-text (message matching-text)))