Don't assume that valid proposal is always one in one round

If a proposer double voted in one round, there could be two or more proposal blocks in the round.
One of the blocks could be finalized in the height.

@majecty

@majecty what happens if there are two proposal blocks in one round?

I'm not sure what is the effect of it. I created this issue since the code depends on an invalid assumption.

If there are two proposal blocks in one round, the finalization time in a network disaster will be increased.

Navigation Menu