Problem

race: limit on 8128 simultaneously alive goroutines is exceeded, dying
FAIL	github.com/ethereum/go-ethereum/swarm/network/stream	462.603s

How to reproduce
time go test -v -race -run TestGetSubscriptionsRPC -count 1000 github.com/ethereum/go-ethereum/swarm/network/stream

Note: My computer froze a few times during the test runs and the test is flaky (#1234).