bug#27563: [PATCH] gnu: ghostscript: Don't write document UUID; use "" as instance UUID.

[Danny Milosavljevic]

> What’s the impact of simply removing all of this from generated PDF
> files?  Should we instead make it optional?

I don't know.  It's just one metadata element - and it's recent.  I mean that 
there are lots of (old) PDF files that don't have it in the first place.

>  For instance, we could
> introduce a new environment variable, say “GHOSTSCRIPT_PDF_UUID”, and
> use that as the document UUID when it’s defined.  

>>In our build
> environments, we’d always set GHOSTSCRIPT_PDF_UUID to a known value to
> ensure determinism.

Upstream definitely doesn't want that - at least not if it's a constant value 
for all PDFs.