
Previously, if the currently installed Nix is too old to evaluate Nixpkgs, then nixos-rebuild would fail and the user had to upgrade Nix manually. Now, as a fallback, we run ‘nix-store -r’ to obtain a binary Nix directly from the binary cache.
*** NixOS *** NixOS is a Linux distribution based on the purely functional package management system Nix. More information can be found at http://nixos.org/nixos and in the manual in doc/manual.