Invalid nonce during mining #317
Description
During mining and creating / receiving transactions it sometimes happens that an agent broadcasts an invalid nonce. This is caused by a delay in a close(chan) which should stop / reset the agent from mining. The nonce that's broadcasted back to the worker is one with an old block.hash which results in an invalid nonce.
For example:
[miner 0] -> mine on 0xaa...c1
[tx 1 comes in] -> work out new state ...
[miner 0] -> finds nonce [broadcast]
[worked out state] -> new block 0x23..a8
[miner 0] -> set nonce (using 0xaa..c1) to [ new block 0x23..a8 ]
[verify] -> invalid