Fix expected string.
Fix expected string.

I got it wrong because gccgo was incorrectly failing to clear
the value when a nonblocking receive did not receive
anything.

R=rsc
CC=golang-dev
http://codereview.appspot.com/194161
abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go