{ fetchgit }:
import (fetchgit {
  url = "https://github.com/nixos/nixpkgs.git";
  # nixos-21.09 as of 2021-03-08
  rev = "1c7f02b0b9f115ccbc122ce39ae99debc1af857a";
  sha256 = "14sichs3hyg4ybcacvzglw97lg747y1ls5lsazv0n5yxv5w06l3d";
})