anchor.diff:    src = fetchFromGitHub {
       owner = "cjdelisle";
       repo = "cjdns";
  -    rev = "97161a5fef6b98ffbba94888587bd9ce733c2278";
  -    sha256 = "0wxiwgjcl4rn71b6hjdlfgv9hjy9d43sypikzcl5z65r7xkrb41j";
  +    rev = "b7681f601dc0ba84c6c710061089f9898247ba4e";
  +    sha256 = "0r59j9x5i1nkd6k8172l9iq95f6c22ymmkrm9nxwxr5dp2bj0qn5";
     };
   
     buildInputs = [ which python27 nodejs ] ++
  
positive.code: 
  let
    version = "15"; # see ${src}/util/version/Version.h
    date = "20150129";
  in
  stdenv.mkDerivation {
    name = "cjdns-${version}-${date}";
  
negative.code:     sed -i 's,/usr/bin/env python,'$(type -P python), \
        $(find contrib -type f)
      mkdir -p $out/share/cjdns
      cp -R contrib tools node_build node_modules $out/share/cjdns/
    '';
  
    meta = with stdenv.lib; {
  