anchor.diff:  
     crypto = buildFromGitHub {
       version = 2;
  -    rev = "b07d8c96772f426812d3fc5530710ec1f3b205e7";
  -    date = "2016-10-26";
  +    rev = "9a6f0a01987842989747adff311d80750ba25530";
  +    date = "2016-12-10";
       owner    = "golang";
       repo     = "crypto";
  -    sha256 = "0cj1gwg0wwvbxgs7w5v6hn882jnh4spayz64r3hdjcl5z5mahh60";
  +    sha256 = "1i9iyixpaqp1b7r5b6m14wji540960hk8psgsw163k208bc1fj1i";
       goPackagePath = "golang.org/x/crypto";
       goPackageAliases = [
         "code.google.com/p/go.crypto"
  
positive.code: 
    ipfs = buildFromGitHub {
      version = 2;
      date = "2016-12-10";
      rev = "93c90020b275298694bdc5b6a484eb4f1d531560";
      owner = "ipfs";
      repo = "go-ipfs";
      sha256 = "0298837x06gnnys0w7jr2yh1242xm3aigg1qhj229iawvnk0s9m9";
      gxSha256 = "0jkq4ja7zajwcy2msrwyp7ghkkj4nr4qhzpvlwylqsmw7kwmd3br";
      subPackages = [
        "cmd/ipfs"
        "cmd/ipfswatch"
  
negative.code: 
    go-multihash = buildFromGitHub {
      version = 2;
      rev = "5be2115933c26c6ae0c4b9c5887a44d8ae5bb753";
      owner  = "multiformats";
      repo   = "go-multihash";
      sha256 = "0qj0pkjqpdadsh0c20mvgfwd8mx4dprb5c97i063bsrk9jyxsdy6";
      goPackageAliases = [ "github.com/jbenet/go-multihash" ];
      propagatedBuildInputs = [
        crypto
        go-base58
      ];
      date = "2016-12-12";
    };
  
    go-multipart-files = buildFromGitHub {
  