anchor.diff:  stdenv.mkDerivation rec {
     pname = "autoconf";
     version = "2.71";
  +  outputs = [ "out" "doc" ];
   
     src = fetchurl {
       url = "mirror://gnu/autoconf/autoconf-${version}.tar.xz";
  
positive.code: { lib, stdenv, fetchurl, m4, perl }:
  
  # Note: this package is used for bootstrapping fetchurl, and thus
  # cannot use fetchpatch! All mutable patches (generated by GitHub or
  
negative.code:     ./2.71-fix-race.patch
    ];
  
    nativeBuildInputs = [ m4 perl texinfo ];
    buildInputs = [ m4 ];
    postBuild = "
      make html
    ";
  
    postInstall = "
      make install-html
    ";
  
    # Work around a known issue in Cygwin.  See
    # http://thread.gmane.org/gmane.comp.sysutils.autoconf.bugs/6822 for
  