Hi Maxime,

>> Sorry, I easily used with-environment-variable*s* because the interface
>> looked convenient, but perhaps I should have used
>> with-environment-variable defined in guix/tests.scm.
>> However, using this one does not seem to solve the problem. Should I
>> modify with-environment-variable*s*?
>
> I didn't know about 'with-environment-variable' (it already does the
> unsetenv!). Just use whatever works (a nested with-environment-variable
> or a modified with-environment-variables), though FWIW I would expect
> using the modified with-environment-variables to result in more compact
> code.

I have attached the v4 patch.