This reverts commit 9d55050773.
As noted by Luke-Jr, under some conditions this will accept transactions which are invalid by the network
rules. This happens when the current block time is head of the median time past and a transaction's
locktime is in the middle.
This could be addressed by changing the rule to MAX(this_block_time, MTP+offset) but this solution and
the particular offset used deserve some consideration.
The lock-time code currently uses CBlock::nTime as the cutoff point for time based locked transactions. This has the unfortunate outcome of creating a perverse incentive for miners to lie about the time of a block in order to collect more fees by including transactions that by wall clock determination have not yet matured. By using CBlockIndex::GetMedianTimePast from the prior block instead, the self-interested miner no longer gains from generating blocks with fraudulent timestamps. Users can compensate for this change by simply adding an hour (3600 seconds) to their time-based lock times.
If enforced, this would be a soft-fork change. This commit only adds the functionality on an unexecuted code path, without changing the behaviour of Bitcoin Core.
Add a field `strDebugMessage` which can be passed to DoS or Invalid,
and queried using GetDebugMessage() to add extra troubleshooting
information to the validation state.
ffd75ad Enable CHECKLOCKTIMEVERIFY as a standard script verify flag (Peter Todd)
bc60b2b Replace NOP2 with CHECKLOCKTIMEVERIFY (BIP65) (Peter Todd)
48e9c57 Move LOCKTIME_THRESHOLD to src/script/script.h (Peter Todd)
99088d6 Make CScriptNum() take nMaxNumSize as an argument (Peter Todd)
