Staking/slashing interoperation issue

[cwgoes]

Revoked validator not unbonded correctly. To reproduce, using https://github.com/cosmos/cosmos-sdk/tree/cwgoes/slashing-staking-bug (which just fakes the validator never signing blocks):

rm -rf ~/.gaiad ~/.gaiacli
gaiad init gen-tx --name cwgoes
gaiad init --gen-txs
gaiad start

After 101 blocks, the validator is revoked (correctly) by slashing, but not unbonded and not passed back correctly to Tendermint as a validator set update (printed temporarily for debugging):

}#614593580B469455F0A3F4F17B5022047CBCF7AF module=consensus 
E[05-29|07:39:58.760] Validator FB98CD1DF8823860CC3039DBD6AC6E71C69DE505 present: false module=x/slashing 
I[05-29|07:39:58.760] Absent validator FB98CD1DF8823860CC3039DBD6AC6E71C69DE505 at height 101 module=x/slashing 
I[05-29|07:39:58.760] Validator FB98CD1DF8823860CC3039DBD6AC6E71C69DE505 past min height of 100 and below signed blocks threshold of 50 module=x/slashing 
I[05-29|07:39:58.761] Validator FB98CD1DF8823860CC3039DBD6AC6E71C69DE505 slashed by fraction 1/100, removed 1/1 shares and burned 1 tokens module=x/stake 
I[05-29|07:39:58.761] Validator FB98CD1DF8823860CC3039DBD6AC6E71C69DE505 revoked module=x/stake 
validator updates: []
I[05-29|07:39:58.761] Executed block                               module=state height=101 validTxs=0 invalidTxs=0

[cwgoes]

CC @rigelrozanski

[rigelrozanski]

Cool thanks for the heads up - wow really excited to have revoking on the go here. Yeah let's write a (failing) test case to demonstrate this

[cwgoes]

Fixed by c8133a0 and 40526d3.

We should add integration tests to cover this, probably as part of #974.