default.nix: say which old Nix version is being used (#435683)

authored by jade and committed by GitHub 1a100725 a51f2b29

+2 -1
+2 -1
default.nix
··· 6 6 7 7 abort '' 8 8 9 - This version of Nixpkgs requires Nix >= ${requiredVersion}, please upgrade: 9 + This version of Nixpkgs requires Nix >= ${requiredVersion} but it is being 10 + evaluated with Nix ${builtins.nixVersion or "(too old to know)"}, please upgrade: 10 11 11 12 - If you are running NixOS, `nixos-rebuild' can be used to upgrade your system. 12 13