emulationstation: get rid of fetchSubmodules

Mental note: I need to automate this!

pkgs/by-name/em/emulationstation/package.nix

@@ -22,6 +22,13 @@ in
 stdenv.mkDerivation {
   inherit (sources.emulationstation) pname version src;
 
+  postUnpack = ''
+    pushd $sourceRoot/external/pugixml
+    cp --verbose --archive ${sources.pugixml.src}/* .
+    chmod --recursive 744 .
+    popd
+  '';
+
   nativeBuildInputs = [
     SDL2
     cmake

pkgs/by-name/em/emulationstation/sources.nix

@@ -12,8 +12,22 @@
         owner = "RetroPie";
         repo = "EmulationStation";
         rev = "v${self.version}";
-        fetchSubmodules = true;
+        hash = "sha256-f2gRkp+3Pp2qnvg2RBzaHPpzhAnwx0+5x1Pe3kD90xE=";
-        hash = "sha256-J5h/578FVe4DXJx/AvpRnCIUpqBeFtmvFhUDYH5SErQ=";
+      };
+    };
+  in
+    self;
+
+  pugixml = let
+    self = {
+      pname = "pugixml";
+      version = "1.8.1";
+
+      src = fetchFromGitHub {
+        owner = "zeux";
+        repo = "pugixml";
+        rev = "v${self.version}";
+        hash = "sha256-LbjTN1hnIbqI79C+gCdwuDG0+B/5yXf7hg0Q+cDFIf4=";
       };
     };
   in