client/simplestreams_images.go
func (r *ProtocolSimpleStreams) GetPrivateImage(fingerprint string, secret string) (*api.Image, string, error) {
	return nil, "", fmt.Errorf("Private images aren't supported by the simplestreams protocol")
}
func (r *ProtocolSimpleStreams) GetPrivateImage(fingerprint string, secret string) (*api.Image, string, error) {
	return nil, "", fmt.Errorf("Private images aren't supported by the simplestreams protocol")
}
// GetPrivateImage isn't relevant for the simplestreams protocol