Re: Unbreaking testnet4

Recent modifications to the Bitcoin testnet, as shared on GitHub (view changes), introduce a significant alteration in the protocol's handling of a forthcoming hardfork. Originally slated to activate at block 150000, the update now targets block 151200 for activation. This adjustment aligns the hardfork with the commencement of epoch 75, a strategic move aimed at minimizing potential errors and confusion within the network. Such precision in timing is crucial for ensuring a smooth transition during the fork.

In addition to the revised activation block number, a major change has been implemented concerning the network's difficulty level at the point of hardfork. Specifically, the difficulty will be reset to 1 million at block 151200. This decision addresses the inflated difficulty levels previously caused by CPU miners, which would have otherwise prolonged block discovery times significantly. The reset aims to balance the mining landscape temporarily, leading to a brief period during epochs 75 to around 78 where blocks could be found rapidly by miners possessing substantial hashpower. Following this phase, the difficulty is programmed to quadruple in the 76th epoch and continue increasing progressively until the system stabilizes back to the standard 10-minute block interval. The choice of 1 million for the difficulty reset strikes a balance; it avoids the chaos of too-frequent block discoveries while also preventing excessively long intervals between blocks. Without such an intervention, the natural difficulty calculation mechanism would extend the duration to find a single block to approximately an hour, drastically delaying the completion of epoch 75 to an estimated three months instead of the planned two weeks.