VersatileImageFieldWarmer regenerate images for delete rendition key set

[roshanshrestha01]

Image are initially created with proper rendition key set.

warmer = VersatileImageFieldWarmer(
                        instance_or_queryset=queryset,
                        rendition_key_set=[('large_horiz', 'crop__1200x600')],
                        image_attr=field,
                        verbose=True,
                    )
warmer.warm()                  

Then, when rendition set sized images are deleted from media/__sized__/ re-running warm doesn't create new image but if we change rendition_key_set to rendtion_key_set=[[('large_horiz', 'crop__1250x600')] images are created. Even when we run delete_sized_images, delete_all_created_images, delete_filtered_images, delete_filtered_sized_images and delete_sized_images. Images are not regenerated