anchor.diff:  
     sys = buildFromGitHub {
       version = 2;
  -    rev = "e4594059fe4cde2daf423055a596c2cd1e6c9adf";
  -    date = "2017-02-23";
  +    rev = "21f2569f6feb83b68a25c98c1b20eca5d4e1e6ae";
  +    date = "2017-02-28";
       owner  = "golang";
       repo   = "sys";
  -    sha256 = "147cippgfp0ijmwgswlkxryigmak20d1ccq8kbgid1vrc9w2jarw";
  +    sha256 = "07fcbvjyadzc70lbky6b4hdxkb0vhxrp41zzz4xansakd8bdq51d";
       goPackagePath = "golang.org/x/sys";
       goPackageAliases = [
         "github.com/golang/sys"
  
positive.code: 
    google-cloud-go = buildFromGitHub {
      version = 2;
      date = "2017-02-23";
      rev = "9b68cf4865e93f379a337b7e957f33de60397a48";
      owner = "GoogleCloudPlatform";
      repo = "google-cloud-go";
      sha256 = "05wgiwbyg0dxzh8gl9fhrknrr9qqp9yxwymkgzfg7m7c1vydy4c7";
      goPackagePath = "cloud.google.com/go";
      goPackageAliases = [
        "google.golang.org/cloud"
  
negative.code: 
    docker = buildFromGitHub {
      version = 2;
      rev = "fe9ab0588606a5566d065bc68ae68f3926ddaa72";
      owner = "docker";
      repo = "docker";
      sha256 = "0an27ky1rzr48774g9d85r6wv9qkfivs4ana2xdabn9hz1qslld4";
      meta.useUnstable = true;
      date = "2017-02-28";
    };
  
    docker_for_nomad = buildFromGitHub {
  