eine kleine reminder

[Eddie Kohler]

One more thing -- you only need to call p->uniqueify() once per packet per
element, because the packet can't get shared until you pass it to another
element.

NOT NECESSARY:
	p = p->uniqueify();
	memcpy(p->data(), "xxx", 3);
	p = p->uniqueify();
	memcpy(p->data() + 10, "yyyy", 5);

THIS IS FINE:
	p = p->uniqueify();
	memcpy(p->data(), "xxx", 3);
	memcpy(p->data() + 10, "yyyy", 5);

love,
ed