33437719c1
When a CacheFile datablock is copied to an in-main datablock, it means that the new copy should be independent of the old copy. In this case certain properties are reset/duplicated. When it is copied to a no-main datablock, we assume this is a copy-on-write copy that's used for evaluating things, in which case the handle and object paths are referenced instead of reset/ duplicated. This prevents us from re-opening the Alembic file every time a new CoW copy is made. The same approach is taken when freeing data (only when an in-main datablock is freed do we actually free the data).