internal/restorable/images.go
func (i *images) remove(img *Image) {
	i.makeStaleIfDependingOnImpl(img)
	delete(i.images, img)
}
func (i *images) remove(img *Image) {
	i.makeStaleIfDependingOnImpl(img)
	delete(i.images, img)
}
// remove removes img from the images.