Upgrading
NIX_PATH="nixpkgs=./nixpkgs" ./upgrade.sh nixos-20.03 > nixpkgs.nix
NIX_PATH="nixpkgs=./nixpkgs" ./upgrade-unstable.sh > nixpkgs-unstable.nix
Then sync.
Syncing
./sync.sh
./sync-unstable.sh
git-repos
git clone --depth=1 --branch nixos-unstable https://github.com/NixOS/nixpkgs.git