Richard Stallman wrote:
>    > So I think RMS's suggestion is the right one, and that we should change Emacs to
>    > display ` (not ') for undisplayable left single quotation mark.  I'll prepare a
>    > patch along those lines assuming there's no objection.
>
> Thanks.  That will fix a significant problem.

You're welcome.  I installed the attached patch.