anchor.diff:  
     oauth2 = buildFromGitHub {
       version = 2;
  -    rev = "b9780ec78894ab900c062d58ee3076cd9b2a4501";
  -    date = "2017-02-14";
  +    rev = "810daf0509f84359cfa9527f6ea4886f1dbabfc5";
  +    date = "2017-02-27";
       owner = "golang";
       repo = "oauth2";
  -    sha256 = "1glr1qdnb6mpp4n32xsi44hy38f5hg1c86qzafp2zcazj6nhxnv7";
  +    sha256 = "08idsyw7g8vnycn6sp4fqh98kjm7qcjpg54pkkw7ny1jynnd6w2v";
       goPackagePath = "golang.org/x/oauth2";
       goPackageAliases = [ "github.com/golang/oauth2" ];
       propagatedBuildInputs = [
  
positive.code:     version = 2;
      owner = "coreos";
      repo = "etcd";
      rev = "15d8ca7726a4ac8536504effe397d166b48494c0";
      sha256 = "169pgqjk0pcllqi1hcncrfnr0qr1a6zwcca9h1ms020sy0dcj2jc";
      buildInputs = [
        bolt
        btree
  
negative.code: 
    sys = buildFromGitHub {
      version = 2;
      rev = "21f2569f6feb83b68a25c98c1b20eca5d4e1e6ae";
      date = "2017-02-28";
      owner  = "golang";
      repo   = "sys";
      sha256 = "07fcbvjyadzc70lbky6b4hdxkb0vhxrp41zzz4xansakd8bdq51d";
      goPackagePath = "golang.org/x/sys";
      goPackageAliases = [
        "github.com/golang/sys"
  