Fix: block commit pox-descendant check in nakamoto

[kantai]

This fixes an issue that showed up in the naka-1 testnet. The leader block commit op in nakamoto is committing to a parent block, not a new block, so there was previously essentially an "off by one" bug in the block commit op evaluation.

This also adds a test for this behavior.

[jferrant]

Thanks for finding this Aaron. Is this at all related to the change I made that had to do with how to select the parent to build atop of in the forked_tenure test? Specifically #4674 ? (asking for my own clarity of the situation)

[kantai]

Thanks for finding this Aaron. Is this at all related to the change I made that had to do with how to select the parent to build atop of in the forked_tenure test? Specifically #4674 ? (asking for my own clarity of the situation)

I don't think so-- at least not directly related. This issue ended up being kind of downstream of some other issues in the testnet, but it was the issue that led to the testnet stalling out completely.

[blockstack-devops]

This pull request has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.