The iterator should not be reset.
The iterator should not be reset.

Previously this meant that when we hit the slow case, we needlessly redid all
the fast work that we'd already done. This gives about ~8-9% speedup on
Deltablue.

xhava/hippyvm,xhava/hippyvm,xhava/hippyvm,xhava/hippyvm,xhava/hippyvm,hippyvm/hippyvm,hippyvm/hippyvm,xhava/hippyvm,hippyvm/hippyvm,hippyvm/hippyvm,hippyvm/hippyvm,xhava/hippyvm,hippyvm/hippyvm,hippyvm/hippyvm