Updates in block signing stake are delayed from tendermint

[brentstone]

While trying to implement the PoS rewards in #388, I've noticed that the voting powers / stakes of validators who sign a block coming from tendermint get updated at a delay of 2 blocks relative to the corresponding update in the namada protocol. Particularly, the information obtained from tendermint is here. This behavior seems consisent with this old comment in our repo and with the Usage description for EndBlock in the abci docs.

It is crucial to get the correct block voting information with the signing validators' voting power since the block rewards are dependent on the stake of the signing validators. A possible solution could involve distributing rewards at a 3 block delay.

Has this ever come across as an issue for the eth-bridge integration? @batconjurer @james-chf @sug0

[batconjurer]

I think we are relying solely on the namada protocol for this, so we haven't run into it.

[brentstone]

Perhaps we can get around this by just ignoring the signing stake given by tendermint and getting the stake from the validator deltas on the namada side. The downside to this is that there will be some "leakage" of the old validator set voting powers into the first two blocks of a new epoch. If we can live with this though, then the solution could be simple.