anchor.diff:  
     google-cloud-go = buildFromGitHub {
       version = 2;
  -    date = "2017-02-28";
  -    rev = "5e7b3ea7ac9326eccc657cc16879281396d1b93a";
  +    date = "2017-03-01";
  +    rev = "34d4e098303a6874a9e2d06ef843722588eae366";
       owner = "GoogleCloudPlatform";
       repo = "google-cloud-go";
  -    sha256 = "1d93w5miy0k4bwsfgiwp3lml7802n9bp7cd05sjf6ccf5xhrza56";
  +    sha256 = "1gay8jkdz3gxa4lafrhrs7asn23nk8ra863jpp7zhqm8myl0wznv";
       goPackagePath = "cloud.google.com/go";
       goPackageAliases = [
         "google.golang.org/cloud"
  
positive.code: 
    text = buildFromGitHub {
      version = 2;
      rev = "0ad425fe45e885577bef05dc1c50f72e33188b16";
      date = "2017-02-26";
      owner = "golang";
      repo = "text";
      sha256 = "1ypynyyslg2vlyzy1ghx7l93x08vqfygyzsywli3p8jhm3b8xnih";
      goPackagePath = "golang.org/x/text";
      goPackageAliases = [ "github.com/golang/text" ];
      excludedPackages = "cmd";
  
negative.code: 
    sys = buildFromGitHub {
      version = 2;
      rev = "76cc09b634294339fa19ec41b5f2a0b3932cea8b";
      date = "2017-03-01";
      owner  = "golang";
      repo   = "sys";
      sha256 = "0vn8whgr4ci43bdga8x0knii6p0r5k4afdw0zmn7iixyw1psrm6f";
      goPackagePath = "golang.org/x/sys";
      goPackageAliases = [
        "github.com/golang/sys"
  