consensus: lower regtest nPowTargetTimespan to 144

This currently has no effect due to fPowNoRetargeting,
except for the getnetworkhashps when called with -1.

It will when the next commit enforces the timewarp attack mitigation on regtest.

src/kernel/chainparams.cpp

@@ -537,7 +537,7 @@ public:
         consensus.SegwitHeight = 0; // Always active unless overridden
         consensus.MinBIP9WarningHeight = 0;
         consensus.powLimit = uint256{"7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff"};
-        consensus.nPowTargetTimespan = 14 * 24 * 60 * 60; // two weeks
+        consensus.nPowTargetTimespan = 24 * 60 * 60; // one day
         consensus.nPowTargetSpacing = 10 * 60;
         consensus.fPowAllowMinDifficultyBlocks = true;
         consensus.enforce_BIP94 = false;

test/functional/rpc_blockchain.py

@@ -58,7 +58,7 @@ TIME_RANGE_STEP = 600  # ten-minute steps
 TIME_RANGE_MTP = TIME_GENESIS_BLOCK + (HEIGHT - 6) * TIME_RANGE_STEP
 TIME_RANGE_TIP = TIME_GENESIS_BLOCK + (HEIGHT - 1) * TIME_RANGE_STEP
 TIME_RANGE_END = TIME_GENESIS_BLOCK + HEIGHT * TIME_RANGE_STEP
-DIFFICULTY_ADJUSTMENT_INTERVAL = 2016
+DIFFICULTY_ADJUSTMENT_INTERVAL = 144
 
 
 class BlockchainTest(BitcoinTestFramework):