anchor.diff:  }).getChannel channel;
   
   let
  +  transform = flags: concatStringsSep ";" (map (subst: subst + flags) [
  +    "s,^[^/]+(.*)$,$main\\1,"
  +    "s,$main/(build|tools)(/.*)?$,$out/\\1\\2,"
  +    "s,$main/third_party(/.*)?$,$bundled\\1,"
  +    "s,$main/sandbox(/.*)?$,$sandbox\\1,"
  +    "s,^/,,"
  +  ]);
  +
     pre42 = versionOlder version "42.0.0.0";
  +
   in stdenv.mkDerivation {
     name = "chromium-source-${version}";
   
  
positive.code: 
    buildInputs = [ python ]; # cannot patch shebangs otherwise
  
    phases = [ "unpackPhase" "patchPhase" "installPhase" ];
  
    opensslPatches = optional useOpenSSL openssl.patches;
  
    prePatch = "patchShebangs .";
  
    patches = if pre42 then [
      ./sandbox_userns_36.patch ./nix_plugin_paths.patch
  
negative.code:     ./nix_plugin_paths_42.patch
    ];
  
    patchPhase = let
      diffmod = sym: "/^${sym} /{s/^${sym} //;${transform ""};s/^/${sym} /}";
      allmods = "${diffmod "---"};${diffmod "\\+\\+\\+"}";
      sedexpr = "/^(---|\\+\\+\\+) *\\/dev\\/null/b;${allmods}";
    in ''
      runHook prePatch
      for i in $patches; do
        header "applying patch $i" 3
        sed -r -e "${sedexpr}" "$i" | patch -d / -p0
        stopNest
      done
      runHook postPatch
    '';
  
    postPatch = ''
      sed -i -r \
        -e 's/-f(stack-protector)(-all)?/-fno-\1/' \
        -e 's|/bin/echo|echo|' \
        -e "/python_arch/s/: *'[^']*'/: '""'/" \
        "$out/build/common.gypi" "$main/chrome/chrome_tests.gypi"
    '' + optionalString useOpenSSL ''
      cat $opensslPatches | patch -p1 -d "$bundled/openssl/openssl"
    '' + optionalString (!pre42) ''
      sed -i -e '/LOG.*no_suid_error/d' \
        "$main/content/browser/browser_main_loop.cc"
    '';
  
    passthru = {
  