anchor.diff:      version = 2;
       owner = "coreos";
       repo = "etcd";
  -    date = "2017-04-20";
  -    rev = "633a4e6b5288ecdbacbb8360c8f202d7c9fa2dc6";
  -    sha256 = "1w8idyajlzpa7xc8bl9kpwggpnjygawgfx07rfgyhq6vr2yy08g7";
  +    date = "2017-04-21";
  +    rev = "a9087ee659e58f26de72c4809ddabd8f58b4a97a";
  +    sha256 = "1qjm9blr6lhbbaxwrahb434a4s6kjda1c8c1p1s8nqj2hlz6jsm4";
       buildInputs = [
         bolt
         btree
  
positive.code: 
    sys = buildFromGitHub {
      version = 2;
      rev = "f3918c30c5c2cb527c0b071a27c35120a6c0719a";
      date = "2017-04-07";
      owner  = "golang";
      repo   = "sys";
      sha256 = "161lxk6wqq8kmz33xs2f8cs3d90mkrvflbnr20mbwm53z3flmirs";
      goPackagePath = "golang.org/x/sys";
      goPackageAliases = [
        "github.com/golang/sys"
  
negative.code: 
    aws-sdk-go = buildFromGitHub {
      version = 2;
      rev = "v1.8.16";
      owner  = "aws";
      repo   = "aws-sdk-go";
      sha256 = "00f7dy7py966i7zwld544n8xpy03cwkhqcrxfyxbz7cakli7596z";
      excludedPackages = "\\(awstesting\\|example\\)";
      buildInputs = [
        tools
  