[mysql backend] Fontra likely doesn't respond well to external renaming of glyphs

[justvanrossum]

• Check how it works, what glif_list + updated_at gives us in that case
• Fix whatever is broken

[justvanrossum]

To paraphrase Fabio: to rename a glyph in-place (keeping the unique ID in the DB) one has to send new glif data with a new glyph name.

RoboCJK does not do that (when renaming it creates a new glyph and deletes the old glyph). So unless Fontra itself will implement renaming glyphs in-place, we cannot really test this.

Maybe there's no need, and Fontra should also do it by creating a new glyph with a new name and deleting the old one.