Fix proxy to override code being called on undos.

source/blender/blenkernel/intern/blendfile.c

@@ -347,7 +347,7 @@ static void setup_app_data(bContext *C,
   /* FIXME: Same as above, readfile's `do_version` do not allow to create new IDs. */
   /* TODO: Once this is definitively validated for 3.0 and option to not do it is removed, add a
    * version bump and check here. */
-  if (!USER_EXPERIMENTAL_TEST(&U, no_proxy_to_override_conversion)) {
+  if (mode != LOAD_UNDO && !USER_EXPERIMENTAL_TEST(&U, no_proxy_to_override_conversion)) {
     BKE_lib_override_library_main_proxy_convert(bmain, reports);
   }