bug#1169: 23.0.60; (substitute-command-keys "\\{...}") adds extra newline

[Chong Yidong]

Johan Bockgård <bojohan@gnu.org> writes:

>> I've now made the change,
>
> This change breaks the highlighting code in `help-make-xrefs' which
> assumes that a list of key bindings produced by substitute-command-keys
> (in `documentation') ends with an extra blank line

Thanks.  I've reverted the change in the emacs-24 branch, and added a
note to the docstring of substitute-command-keys that the two newlines
are needed by `help-make-xrefs'.