net/http: fix bug in error checking
net/http: fix bug in error checking

Thanks to josef86@gmail.com for pointing this out.

R=golang-dev, iant
CC=golang-dev
http://codereview.appspot.com/5477092
abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go