// update metadata.
func (er erasureObjects) CopyObject(ctx context.Context, srcBucket, srcObject, dstBucket, dstObject string, srcInfo ObjectInfo, srcOpts, dstOpts ObjectOptions) (oi ObjectInfo, err error) {
	if !dstOpts.NoAuditLog {
		auditObjectErasureSet(ctx, dstObject, &er)
	}

	// This call shouldn't be used for anything other than metadata updates or adding self referential versions.