net: fix spurious EADDRNOTAVAIL errors
net: fix spurious EADDRNOTAVAIL errors

R=golang-dev, fullung
CC=golang-dev
http://codereview.appspot.com/6443085
abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go