anchor.diff:  
     tools = buildFromGitHub {
       version = 3;
  -    rev = "3da34b1b520a543128e8441cd2ffffc383111d03";
  -    date = "2017-07-17";
  +    rev = "fcc44a6330868f7bdb7285effa1a0666eede46ac";
  +    date = "2017-08-01";
       owner = "golang";
       repo = "tools";
  -    sha256 = "18qk09bdj26pd4iym8avpicg2kz1ldnr79xc0fljvay17sxkr63n";
  +    sha256 = "14nmp27wj4xi4bjwk7rqblrs2yiyynvm6nfaqgayl9zl26zgav3f";
       goPackagePath = "golang.org/x/tools";
   
       preConfigure = ''
  
positive.code: 
    protobuf = buildFromGitHub {
      version = 3;
      rev = "0a4f71a498b7c4812f64969510bcb4eca251e33a";
      date = "2017-07-12";
      owner = "golang";
      repo = "protobuf";
      sha256 = "1a3csg3m7s3yi6kwd2n6qfyml4pifgnm7y5vylgva8mh7gp9j7hj";
      goPackagePath = "github.com/golang/protobuf";
      buildInputs = [
        genproto_protobuf
  
negative.code: 
    net = buildFromGitHub {
      version = 3;
      rev = "f5079bd7f6f74e23c4d65efa0f4ce14cbd6a3c0f";
      date = "2017-07-26";
      owner = "golang";
      repo = "net";
      sha256 = "0z8w0ycj67naxwxfnzwd5srpa7h7f41imvv2vigvd9cr8s6i2iq9";
      goPackagePath = "golang.org/x/net";
      goPackageAliases = [
        "github.com/hashicorp/go.net"
  