anchor.diff:  
   stdenv.mkDerivation rec {
     pname = "devhelp";
  -  version = "40.1";
  +  version = "41.2";
  +
  +  outputs = [ "out" "devdoc" ];
   
     src = fetchurl {
       url = "mirror://gnome/sources/devhelp/${lib.versions.major version}/${pname}-${version}.tar.xz";
  -    sha256 = "PorZPoSEtEgjyuR0ov2dziLtbs0lZVWSzq17G2gya7s=";
  +    sha256 = "7KqQsPTaqPsgMPbcaQv1M/+Zp3NDf+Dhis/oLZl/YNI=";
     };
   
     nativeBuildInputs = [
  
positive.code:     appstream-glib
      gobject-introspection
      python3
    ];
  
    buildInputs = [
      glib
      gtk3
      webkitgtk
      amtk
      gnome.adwaita-icon-theme
      gsettings-desktop-schemas
    ];
  
    doCheck = true;
  
    postPatch = ''
      chmod +x meson_post_install.py # patchShebangs requires executable file
      patchShebangs meson_post_install.py
    '';
  
    preFixup = ''
  
negative.code:       # https://gitlab.gnome.org/GNOME/devhelp/issues/14
        --prefix XDG_DATA_DIRS : "${shared-mime-info}/share"
      )
    '';
  
    postFixup = ''
      # Cannot be in postInstall, otherwise _multioutDocs hook in preFixup will move right back.
      moveToOutput share/doc/devhelp-3 "$devdoc"
    '';
  
    passthru = {
  