consensus: fix wrong proposer schedule for `InitChain` validators (#5329)

Fixes #5328.

CHANGELOG_PENDING.md

@@ -46,4 +46,6 @@ Friendly reminder, we have a [bug bounty program](https://hackerone.com/tendermi
 
 - [statesync] \#5320 Broadcast snapshot request to all pre-connected peers on start (@erikgrinaker)
 
+- [consensus] \#5329 Fix wrong proposer schedule for validators returned by `InitChain` (@erikgrinaker)
+
 - [light] [\#5307](https://github.com/tendermint/tendermint/pull/5307) Persist correct proposer priority in light client validator sets (@cmwaters)

consensus/replay.go

@@ -339,7 +339,7 @@ func (h *Handshaker) ReplayBlocks(
 					return nil, err
 				}
 				state.Validators = types.NewValidatorSet(vals)
-				state.NextValidators = types.NewValidatorSet(vals)
+				state.NextValidators = types.NewValidatorSet(vals).CopyIncrementProposerPriority(1)
 			} else if len(h.genDoc.Validators) == 0 {
 				// If validator set is not set in genesis and still empty after InitChain, exit.
 				return nil, fmt.Errorf("validator set is nil in genesis and still empty after InitChain")