TestIDService is flaky

[aarshkshah1992]

@Stebalien

Tackling this with priority:

https://travis-ci.com/github/libp2p/go-libp2p/builds/167056100.

[aarshkshah1992]

It's really hard to reproduce the flakiness:

aarshshah@Aarshs-MacBook-Pro identify % go test -race -count=50 -run TestIDService
PASS
ok  	github.com/libp2p/go-libp2p/p2p/protocol/identify	380.844s

But, my suspicion is that it could happen if the subscriber was created after the event was emitted. This could happen if the Connected notification triggers/finishes an Identify before the subscriber is created.

We should create the EvtPeerIdentificationCompleted subscriber before we connect to the other peer.

Creating a patch for this and closing this. Let's re-open if we see this again.

[vyzo]

travis is very slow and may be running with a single processor.
We have no end in grief in the pubsub tests, which are by necessity timing dependent :(