net/http: make a test more paranoid & reliable on Windows, maybe.
net/http: make a test more paranoid & reliable on Windows, maybe.

Part of diagnosing issue 3050.

R=golang-dev, rsc
CC=golang-dev
http://codereview.appspot.com/5707056

firebitsbr/golang-old,wesolows/golang-old,wesolows/golang,wesolows/golang-old,wesolows/golang,wesolows/golang,wesolows/golang,wesolows/golang-old,firebitsbr/golang-old,wesolows/golang-old,firebitsbr/golang-old,wesolows/golang,wesolows/golang-old,wesolows/golang,firebitsbr/golang-old,wesolows/golang-old,firebitsbr/golang-old,wesolows/golang-old,firebitsbr/golang-old,wesolows/golang,firebitsbr/golang-old,firebitsbr/golang-old