add NIX_BIN_PREFIX to hardcode nix

[Mic92]

No description provided.

[cpcloud]

I just bisected my configuration, and somehow this commit causes every line of stdout to be duplicated in any project that uses direnv.

I'm using home-manager with programs.direnv.enableNixDirenvIntegration = true;.

[cpcloud]

Ok, after changing nixFlakes to nix in default.nix on master, the double logging goes away. Is this a bug in the nix binaries under nixFlakes?

[cpcloud]

In the meantime, it's easy enough to override nixFlakes with nix in an overlay, since I'm not using flakes right now.

[Mic92]

This was a bug in nixUnstable at some point. It got fixed however eventually. You must use an old version.

[cpcloud]

I'm using niv to manage nixpkgs and running against nixos-unstable-small, so I assume that I have the latest-but-not-master-mostly-reliably-passing versions of everything.