If, due to invalidation / reconsideration of blocks, the previous best header is no longer valid / guaranteed to be the most‐work header in our block‐index not known to be invalid, recalculate it.
If, due to invalidation / reconsideration of blocks, the previous best header is no longer valid / guaranteed to be the most‐work header in our block‐index not known to be invalid, recalculate it.