anchor.diff:  
     sys = buildFromGitHub {
       version = 6;
  -    rev = "c488ab1dd8481ef762f96a79a9577c27825be697";
  -    date = "2018-03-21";
  +    rev = "13d03a9a82fba647c21a0ef8fba44a795d0f0835";
  +    date = "2018-03-26";
       owner  = "golang";
       repo   = "sys";
  -    sha256 = "1hh52maap0vcvv4r5k23v6zfjvylwpbgw5dgldjwihdp2lnz8w43";
  +    sha256 = "0ibj051npxdyny8c69h08s28zc10a2gpjzxzj8z15hqb8f29rzm1";
       goPackagePath = "golang.org/x/sys";
     };
   
  
positive.code:     version = 6;
      owner = "elves";
      repo = "elvish";
      rev = "a13c7c2a51cd7b096401c52a617523b3192fc77c";
      sha256 = "0y89qc60ks8wn7mhrhlblkprm8yflz5ndyda8j9wkksrsw2p2pvn";
      propagatedBuildInputs = [
        bolt
        go-isatty
  
negative.code:       sys
      ];
      meta.useUnstable = true;
      date = "2018-03-24";
    };
  
    eme = buildFromGitHub {
  