anchor.diff:  
     image-spec = buildFromGitHub {
       version = 3;
  -    rev = "1b24aca6c83b826936087d56271f34fcef46c7b2";
  +    rev = "28462ef6944123de00cf27e812309cbf5d82da71";
       owner  = "opencontainers";
       repo   = "image-spec";
  -    sha256 = "07gm3why8ma4r921d5y8sb03v093g2i2nf1x6856m1gr76wih5bx";
  -    date = "2017-06-27";
  +    sha256 = "00kq8l80cqvhzvh0k2p0nbzy3kwyjpnhky8kvw1lnjkkgmgz527q";
  +    date = "2017-06-28";
       propagatedBuildInputs = [
         errors
         go4
  
positive.code: 
    google-cloud-go = buildFromGitHub {
      version = 3;
      date = "2017-06-28";
      rev = "f6bedb5a8dbce75418580cedf5c2434c78d06cfa";
      owner = "GoogleCloudPlatform";
      repo = "google-cloud-go";
      sha256 = "0593hnxfm8l466pzci385yrpqxh22as42l2vyrasr9w0pa5k0c11";
      goPackagePath = "cloud.google.com/go";
      goPackageAliases = [
        "google.golang.org/cloud"
  
negative.code: 
    net = buildFromGitHub {
      version = 3;
      rev = "1f9224279e98554b6a6432d4dd998a739f8b2b7c";
      date = "2017-06-29";
      owner  = "golang";
      repo   = "net";
      sha256 = "0y2sh3a4zns06d77r1ql9h07g7hpycrb303lxd2048sv8ihgwa3j";
      goPackagePath = "golang.org/x/net";
      goPackageAliases = [
        "github.com/hashicorp/go.net"
  