anchor.diff:  
   with stdenv.lib;
   let
  -  version = "2.6.1";
  +  version = "2.7.0";
     audio = optionalString (hasSuffix "linux" stdenv.system) "alsa,"
       + optionalString pulseSupport "pa,"
       + optionalString sdlSupport "sdl,";
  
positive.code: 
    patches = [
      ./no-etc-install.patch
      (fetchpatch {
        url = "http://git.qemu.org/?p=qemu.git;a=patch;h=fff39a7ad09da07ef490de05c92c91f22f8002f2";
        name = "9pfs-forbid-illegal-path-names.patch";
        sha256 = "081j85p6m7s1cfh3aq1i2av2fsiarlri9gs939s0wvc6pdyb4b70";
      })
      (fetchpatch {
        url = "http://git.qemu.org/?p=qemu.git;a=patch;h=805b5d98c649d26fc44d2d7755a97f18e62b438a";
        name = "9pfs-forbid-.-and-..-in-file-names.patch";
        sha256 = "0km6knll492dx745gx37bi6dhmz08cmjiyf479ajkykp0aljii24";
      })
      (fetchpatch {
        url = "http://git.qemu.org/?p=qemu.git;a=patch;h=56f101ecce0eafd09e2daf1c4eeb1377d6959261";
        name = "9pfs-directory-traversal-CVE-2016-7116.patch";
        sha256 = "06pr070qj19w5mjxr36bcqxmgpiczncigqsbwfc8ncjhm1h7dmry";
      })
    ];
  
    configureFlags =
      [ "--smbd=smbd" # use `smbd' from $PATH
  
negative.code: 
    src = fetchurl {
      url = "http://wiki.qemu.org/download/qemu-${version}.tar.bz2";
      sha256 = "0lqyz01z90nvxpc3nx4djbci7hx62cwvs5zwd6phssds0sap6vij";
    };
  
    buildInputs =
  