nixpkgs/pkgs/misc/bleeding-edge-fetch-info/nix_repository_manager.nix

 args: with args; fetchurl { 
  url = http://mawercer.de/~nix/repos/nix_repository_manager.tar.gz;
  sha256 = "6422ef73ea0efceed6ee8e0c6349826813a921ef6f15f68eacc11a3cf1304b37";}