Quick and lazy reply before the sleep comes,

Seems like a ‘simple’ case of the packages not being ordered 
(enough): 
https://www.tobias.gr/guix-package.cache.diffoscope.html/#lib---guix---package.cache---strings---all---

(Sorry for the ad-hoc URL, I'll keep it up until this bug report 
is closed!)

Kind regards,

T G-R