Ah, it turns out that I wrote my message before reading the ongoing discussion on locales. What a coincidence! So we were at least two being bitten by this bug (yes, yes) at the same time! I do not think it is reasonable to break systems for saving 100MB.
The code of glibc states ;; Installing a locale archive with all the locales is to ;; expensive (~100 MiB), so we rely on users to install the ;; locales they really want. But how do I do that? I wondered if there was an additional "locale" output of glibc, but there is not. $ guix package -A locale does not return anything useful. There is a section 6.2.6 in the manual, but it only speaks about GSD, not about Guix inside other systems. So there needs to be a simple way to install locales to be used by Guix packages, and it needs to be documented. Or the patch could be reverted. Andreas