[Miner] miner issues TenureExtend block if the first Nakamoto sortition is empty

[jcnelson]

In the event that the first sortition in the Nakamoto epoch has no winner, all miners issue a TenureExtend tenure-change transaction instead of a TenureChange transaction, leading to a chain halt.

[diwakergupta]

From the referenced commits, looks like this was fixed. Can this be closed @jcnelson @saralab ?

[blockstack-devops]

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