Fix a step regression bug in Tendermint::worker::new_blocks

[foriequal0]

We can observe the regression in the node's peer state update log.

Reconstructed timeline of the node from log of other nodes:
(Timestamp may not be monotonic due to the network recover)

1. Being partitioned after sending vote for height: 468212, view: 0, step: Precommit.
2. Recovered from partition around height: 468215, view: 0, step: Precommit
3. Sends pending previous messages for { height: 468212, view: 0, step: Precommit }

Peer state update step: VoteStep { height: 468212, view: 0, step: Precommit }
Received RequestMessage for VoteStep { height: 468212, view: 0, step: Precommit }

4. Sends body request.

Received body request from Global xxx.xxx.xxx.xxx:9486

5. Receives 468213, 468214 (proposal)

Peer #Global xxx.xxx.xxx.xxx:9486 status update: total_score: 37299169980127389355583666307342289824362786282821, best_hash: 0xde5c…9196

• Tendermint::worker::new_blocks([468213, 468214(proposal)], [])
  • height_changed = true;
self.move_to_height(468213);
self.save_last_confirmed_view(0);
  • self.on_imported_proposal(468214);
    • self.move_to_height(468214);
self.move_to_step(Step::Prevote);

      Peer state update step: VoteStep { height: 468214, view: 0, step: Prevote } proposal None
      

      • self.request_messages_to_all({ 468214, 0, Prevote });

      Received RequestMessage for VoteStep { height: 468214, view: 0, step: Prevote }
      

      • self.generate_and_broadcast_message();

      VoteOn { step: VoteStep { height: 468214, view: 0, step: Prevote }, block_hash: None }
      

  • self.move_to_step(Step::Propose); } // this is a regression

    Peer state update step: VoteStep { height: 468214, view: 0, step: Propose } proposal None
    

    • network::Event::SetTimerStep { Step::Propose }

6. on_timeout for Step::Propose
   • self.move_to_step(Step::Prevote); }

     Peer state update step: VoteStep { height: 468214, view: 0, step: Prevote } proposal Some
     

     • self.votes_received = BitSet::new();
     • self.request_messages_to_all({ 468214, 0, Prevote });

       Received RequestMessage for VoteStep { height: 468214, view: 0, step: Prevote }
       

     • self.generate_and_broadcast_message(); // this is a double vote

       VoteOn { step: VoteStep { height: 468214, view: 0, step: Prevote }, block_hash: Some }
       

Node id:
350381008       388247645       729999778       167729828
        760824946       913276364       744880070
Log timestamp (Seconds after 2019-09-06 01:03)          Log message
47.4196 45.2747 41.7924 41.7540 33.3642 23.2340 25.8503	Peer state update step: VoteStep { height: 468212, view: 0, step: Precommit }
                                        25.8494 26.0468	Received RequestMessage for VoteStep { height: 468212, view: 0, step: Precommit } ...
                                                26.0472	Received body request from Global xxx.xxx.xxx.xxx:9486

47.4215 45.2721 41.7926 41.7545 33.3635 26.2126 26.2135	Peer #Global xxx.xxx.xxx.xxx:9486 status update: total_score: 37299169980127389355583666307342289824362786282821, best_hash: 0xde5c…9196

47.4226         41.7933         33.3646                 Peer state update step: VoteStep { height: 468214, view: 0, step: Prevote } proposal None
                                        26.3621         Received RequestMessage for VoteStep { height: 468214, view: 0, step: Prevote }
                41.7965         33.3651 26.3634 26.4077 VoteOn { step: VoteStep { height: 468214, view: 0, step: Prevote }, block_hash: None }

47.4232	45.2751         41.7552	33.3653                 Peer state update step: VoteStep { height: 468214, view: 0, step: Propose } proposal None

        45.2762                                         Peer state update step: VoteStep { height: 468214, view: 0, step: Prevote } proposal Some
                                        29.2148         Received RequestMessage for VoteStep { height: 468214, view: 0, step: Prevote }
                41.7970         33.3658         29.2175 VoteOn { step: VoteStep { height: 468214, view: 0, step: Prevote }, block_hash: Some }
47.4241	45.2740         41.7564         29.7166         Peer #Global xxx.xxx.xxx.xxx:9486 status update: total_score: 37299169980127389355583666307342289824362786282821, best_hash: 0xde5c…9196

167729828.log
350381008.log
388247645.log
729999778.log
744880070.log
760824946.log
913276364.log

[majecty]

Why is the self.height needed?
It seems the two expressions are the same.

1. (self.height, Step::Propose) > (self.height, self.step.to_step())
2. Step::Propose > self.step.to_step()