anchor.diff: -{ stdenv, lib, go, buildGoPackage, fetchFromGitHub }:
  +{ stdenv, go, buildGoPackage, fetchFromGitHub }:
   
   buildGoPackage rec {
     name = "alertmanager-${version}";
  -  version = "0.5.0";
  +  version = "0.5.1";
     rev = "v${version}";
   
     goPackagePath = "github.com/prometheus/alertmanager";
  
positive.code:     description = "Alert dispatcher for the Prometheus monitoring system";
      homepage = https://github.com/prometheus/alertmanager;
      license = licenses.asl20;
      maintainers = with maintainers; [ benley ];
      platforms = platforms.unix;
    };
  }
  
negative.code:     inherit rev;
      owner = "prometheus";
      repo = "alertmanager";
      sha256 = "1z0f8jqbd4v00634qcs41h1zb70ahl63svlzn33gavripk84hwzq";
    };
  
    # Tests exist, but seem to clash with the firewall.
  