upgrade-package.nix

{ pkgs ? import ./. {
    overlays = [
      (self: super:
      {
        callPackage = f: args:
          let
            drv = super.runCommandNoCC "hello-override" {} ''
              mkdir $out
              substitute ${f}/default.nix $out/default.nix \
                --replace 2.10 2.11 \
                --replace 0ssi1wpaf7plaswqqjwigppsg5fyh99vdlb9kzl7c9lng89ndq1i 0000000000000000000000000000000000000000000000000000
            '';
          in
            if f == ./pkgs/applications/misc/hello
            then super.callPackage (import drv) args
            else super.callPackage f args;
      })
    ];
  }
}:

pkgs.callPackage ./pkgs/applications/misc/hello {}