The test failed on one of the builders with:
timeout_test.go:594: 	ln.Accept: accept tcp 127.0.0.1:19373: use of closed network connection
http://build.golang.org/log/e83f4a152b37071b9d079096e15913811ad296b5

R=golang-dev, bradfitz, dave, mikioh.mikioh, remyoudompheng, rsc
CC=golang-dev
https://golang.org/cl/6859043