* updateToState exits early if the state isn't new, which happens after
* fast syncing. This results in not sending a NewRoundStep message. The mempool
* reactor depends on PeerState, which is updated by NewRoundStep
* messages. If the peer never sends a NewRoundStep, the mempool reactor
* will think they're behind, and never forward transactions. Note this
* only happens when `create_empty_blocks = false`, because otherwise
* peers will move through the consensus state and send a NewRoundStep
* for a new step soon anyways. Simple fix is just to send the
* NewRoundStep message during updateToState even if exit early
https://play.golang.org/p/gN21yO9IRs3
```
func waitWithCancel(f func() *clist.CElement, ctx context.Context) *clist.CElement {
el := make(chan *clist.CElement, 1)
select {
case el <- f():
```
will just run f() blockingly, so this doesn't change much in terms of behavior.
if we call it after, we might receive a "fresh" transaction from
`broadcast_tx_sync` before old transactions (which were not
committed).
Refs #1091
```
Commit is called with a lock on the mempool, meaning no calls to CheckTx
can start. However, since CheckTx is called async in the mempool
connection, some CheckTx might have already "sailed", when the lock is
released in the mempool and Commit proceeds.
Then, that spurious CheckTx has not yet "begun" in the ABCI app (stuck
in transport?). Instead, ABCI app manages to start to process the
Commit. Next, the spurious, "sailed" CheckTx happens in the wrong place.
```
