We are seeing proposers being reselected for a few blocks in a row in the game_of_stakes network

Here is what we were able to see:

This looks like that in rounds > 0 the proposer priority is not decremented for the actual proposer. This is most likely a bug in the proposer selection.

What is actually happening is:

Block 1 R0: Val C: round skip <- prio decremented
Block 1 R1: Val B: round skip
Block 1 R2: Val A: Proposes

Block 2 R0: Val B: round skip <- prio decremented
Block 2 R1: Val C: propose

Block 3 R0: Val C: propose <- prio decremented

==

I would expect the following:

Block 1 R0: Val C: round skip <- prio decremented
Block 1 R1: Val B: round skip <- prio decremented
Block 1 R2: Val A: Proposes <- prio decremented

Block 2 R1: Val D: propose <- prio decremented

==

NextValidators is already specified 1 block ahead so any updates to the proposer priority at the previous height are ignored (e.g. round skips).

In updateState instead of nValSet.IncrementProposerPriority(1) we could do nValSet.IncrementProposerPriority(n_rounds_prev_block)

CC: @ebuchman @zmanian @jaekwon @ValarDragon @milosevic @melekes