ng0 <ng0@infotropique.org> writes:

…

>> > We have Nix in (gnu packages package-management).
>> > Why do you fetch it again when we could just add
>> > another output to the nix package?
>> 
>> Didn't think about this.  It will not fetch again if sources are same, I
>> guess.  But it will be more proper way for sure.  The problem is that
>> I'm not very familiar with mixing build systems for now.  This bug
>> report probably needs to wait me or somebody else will do it.

…

> Yet another option: inherit the package "nix" and adjust accordingly.

I think this is the best option.