anchor.diff:  
     syncthing = buildFromGitHub rec {
       version = "0.12.16";
  -    rev = "v0.12.20";
  +    rev = "v0.12.21";
       owner = "syncthing";
       repo = "syncthing";
  -    sha256 = "133mb8n91izqif35xfs5k5kw74i14gvfv2s9vvx2n6wvqcbf4w9y";
  +    sha256 = "18bq8677nnnwkns0diy3hmzdlhyq6c3faqddiwz4ysbl3vjyr847";
       buildFlags = [ "-tags noupgrade,release" ];
       buildInputs = [
         go-lz4 du luhn xdr snappy ratelimit osext
  
positive.code: 
  
    protobuf = buildFromGitHub {
      rev = "62e4364d64b32762febb61f2c88c0a29bc49a225";
      date = "2016-03-17";
      owner = "golang";
      repo = "protobuf";
      sha256 = "1yxzgxims3hqnbnfqy74m7n823gnxqf8rqi4wff3zyxw9kq32zl2";
      goPackagePath = "github.com/golang/protobuf";
      goPackageAliases = [ "code.google.com/p/goprotobuf" ];
    };
  
negative.code:   };
  
    net = buildFromGitHub {
      rev = "4876518f9e71663000c348837735820161a42df7";
      date = "2016-03-22";
      owner  = "golang";
      repo   = "net";
      sha256 = "0vbs6ikshx0qyxwf0pk5b16g21zwcibi62k65qb43qg58ryg7x95";
      goPackagePath = "golang.org/x/net";
      goPackageAliases = [
        "code.google.com/p/go.net"
  