bug#19918: 25.0.50; links in *Backtrace* & *Help* go to the wrong function definitions

[Drew Adams]

> Do you have a recipe not involving your own code?

The point is that the help button does not reflect the fact
that the command was redefined.

The redefining code (in bookmark+-bmu.el, at top level) is
simply this:

(defun bookmark-bmenu-list (&optional filteredp msg-p)
  "..."
  (interactive "i\np")
  ...)

The problem is with the button link - it has apparently
hard-coded the address of the original definition of
this command, in standard library bookmark.el.

That's the bug.