anchor.diff:  
     persistent1 = prevStage: self: super: with prevStage; {
       inherit
  -      zlib patchutils m4 scons flex perl bison unifdef unzip openssl icu python
  +      zlib patchutils m4 scons flex perl bison unifdef unzip openssl python
         libxml2 gettext sharutils gmp libarchive ncurses pkg-config libedit groff
         openssh sqlite sed serf openldap db cyrus-sasl expat apr-util subversion xz
         findfreetype libssh curl cmake autoconf automake libtool ed cpio coreutils;
   
       darwin = super.darwin // {
         inherit (darwin)
  -        dyld Libsystem xnu configd libdispatch libclosure launchd;
  +        dyld Libsystem xnu configd ICU libdispatch libclosure launchd;
       };
     };
   
  
positive.code:     };
  
      allowedRequisites = (with pkgs; [
        xz.out xz.bin libcxx libcxxabi icu.out gmp.out gnumake findutils bzip2.out
        bzip2.bin llvmPackages.llvm llvmPackages.llvm.lib zlib.out zlib.dev libffi.out coreutils ed diffutils gnutar
        gzip ncurses.out ncurses.dev ncurses.man gnused bash gawk
        gnugrep llvmPackages.clang-unwrapped patch pcre.out binutils-raw.out
        binutils-raw.dev binutils gettext
      ]) ++ (with pkgs.darwin; [
        dyld Libsystem CF cctools libiconv locale
      ]);
  
      overrides = self: super:
  
negative.code:     };
  
      darwin = super.darwin // {
        inherit (darwin) dyld ICU Libsystem cctools libiconv;
      };
    } // lib.optionalAttrs (super.targetPlatform == localSystem) {
      # Need to get rid of these when cross-compiling.
  