anchor.diff:  , cmake, libssh2, openssl, mysql, darwin, git, perl, pcre, gecode_3, curl
   , msgpack, qt59, libsodium, snappy, libossp_uuid, lxc, libpcap, xorg, gtk2, buildRubyGem
   , cairo, re2, rake, gobject-introspection, gdk_pixbuf, zeromq, czmq, graphicsmagick, libcxx
  -, file, libvirt, glib, vips, taglib, libopus
  +, file, libvirt, glib, vips, taglib, libopus, linux-pam, libidn, protobuf
   , libselinux ? null, libsepol ? null
   }@args:
   
  
positive.code: 
    iconv = attrs: {
      buildFlags = lib.optional stdenv.isDarwin "--with-iconv-dir=${libiconv}";
    };
  
    # disable bundle install as it can't install anything in addition to what is
  
negative.code:     buildInputs = [ imagemagick which ];
    };
  
    rpam2 = attrs: {
      buildInputs = [ linux-pam ];
    };
  
    ruby-libvirt = attrs: {
      buildInputs = [ libvirt pkgconfig ];
      buildFlags = [
  