> I’d prefer clearer case analysis as shown above.

OK, what do you think about this diff?  If everything is fine, I’ll make
it output generations in the recutils format.

(Is it necessary to mention that ‘maybe-comma-separated-integers’ accepts
something like ‘1,2,3,’ or ‘1,,,2’.  Or should I change the function?)

I don’t know if the code works with non-default profiles because my
store is broken.  When I try to install or build a new package (with or
without substitutes), I get the following message:

guix package: error: build failed: getting attributes of path `/nix/store/fcwh19ljibqjfx0c3cwnwcc7p31aq227-glibc-2.17-locales': No such file or directory

I’ve already tried to run ‘guix gc’, but it didn’t help.