anchor.diff:        cat "$out" 1>&2
         exit 1
       fi
  +
       ${patchutils}/bin/filterdiff \
         -p1 \
         ${builtins.toString (builtins.map (x: "-x ${lib.escapeShellArg x}") excludes)} \
  
positive.code:   # 0.3.4 would change hashes: https://github.com/NixOS/nixpkgs/issues/25154
    patchutils = buildPackages.patchutils_0_3_3;
  in
  { stripLen ? 0, extraPrefix ? null, excludes ? [], includes ? [], revert ? false, ... }@args:
  
  fetchurl ({
    postFetch = ''
      tmpfile="$TMPDIR/patch"
      if [ ! -s "$out" ]; then
        echo "error: Fetched patch file '$out' is empty!" 1>&2
        exit 1
      fi
      "${patchutils}/bin/lsdiff" "$out" \
        | sort -u | sed -e 's/[*?]/\\&/g' \
        | xargs -I{} \
  
negative.code:            --addnewprefix=b/${extraPrefix} \
          ''} \
          --clean "$out" > "$tmpfile"
  
      if [ ! -s "$tmpfile" ]; then
        echo "error: Normalized patch '$tmpfile' is empty (while the fetched file was not)!" 1>&2
        echo "Did you maybe fetch a HTML representation of a patch instead of a raw patch?" 1>&2
  