> Can you run ‘make clean && make’ in Guix, in case the .drv path was
> retained elsewhere?

Same error.

Also, 'make clean' returned some warnings.

# make clean

[...]

make[1]: Entering directory `/home/guix-savannah'

test -z "nix-setuid-helper" || rm -f nix-setuid-helper
find "/home/guix-savannah/test-tmp" | xargs chmod +w
find: `/home/guix-savannah/test-tmp': No such file or directory
chmod: missing operand after ‘+w’
Try 'chmod --help' for more information.
make[1]: [clean-local] Error 123 (ignored)

[...]

make[1]: Leaving directory `/home/guix-savannah'

Nikita