net/rpc: fix race in TestClientWriteError test Fixes issue 2752.
net/rpc: fix race in TestClientWriteError test
Fixes issue 2752.

R=golang-dev, mpimenov, r
CC=golang-dev
http://codereview.appspot.com/5571062
abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go