net/http: ignore paths on CONNECT requests in ServeMux
net/http: ignore paths on CONNECT requests in ServeMux

Fixes issue 3538

R=golang-dev, adg, rsc
CC=golang-dev
http://codereview.appspot.com/6117058
abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go