Merge #6703: fix: intermittent error in feature_dip3_v19.py

d1e820f fix: not just skip chainlock, but ignore only _best_ chainlock (Konstantin Akimov)
cb42761 feat: just skip chainlock for cbtx if it is legacy scheme signed (Konstantin Akimov)
35161cb test: simplify feature_dip3_v19 test by excluding v20 out of scope (Konstantin Akimov)
63f509d fix: intermittent error in feature_dip3_v19.py (Konstantin Akimov)

Pull request description:

  ## Issue being fixed or feature implemented
  #6702

  It can happen on Regtest or Devnet if v20 is just activated but the best chainlock is still in legacy (pre-v19) scheme.

  It causes errors on CI similar to this one:

      2025-05-31T10:28:49.821000Z TestFramework (INFO): Checking that protxs with duplicate EvoNodes fields are rejected
      2025-05-31T10:29:50.653000Z TestFramework (INFO): dynamically_prepare_masternode failed
      2025-05-31T10:30:50.784000Z TestFramework (ERROR): Assertion failed
      Traceback (most recent call last):
        File "DASH/test/functional/test_framework/test_framework.py", line 162, in main
          self.run_test()
        File "DASH/test/functional/feature_dip3_v19.py", line 87, in run_test
          self.dynamically_evo_update_service(evo_info_0, 8)
        File "DASH/test/functional/test_framework/test_framework.py", line 1384, in dynamically_evo_update_service
          tip = self.generate(self.nodes[0], 1)[0]
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        File "DASH/test/functional/test_framework/test_framework.py", line 805, in generate
          sync_fun() if sync_fun else self.sync_all()
                                      ^^^^^^^^^^^^^^^
        File "DASH/test/functional/test_framework/test_framework.py", line 874, in sync_all
          self.sync_blocks(nodes)
        File "DASH/test/functional/test_framework/test_framework.py", line 840, in sync_blocks
          raise AssertionError("Block sync timed out after {}s:{}".format(
      AssertionError: Block sync timed out after 60s:
        '4227eea732e686fcf608bcbc5525a02336bb69c2eed70e8a59d6439b2122190f'
        '4227eea732e686fcf608bcbc5525a02336bb69c2eed70e8a59d6439b2122190f'
        '4227eea732e686fcf608bcbc5525a02336bb69c2eed70e8a59d6439b2122190f'
        '4227eea732e686fcf608bcbc5525a02336bb69c2eed70e8a59d6439b2122190f'
        '4227eea732e686fcf608bcbc5525a02336bb69c2eed70e8a59d6439b2122190f'
        '4227eea732e686fcf608bcbc5525a02336bb69c2eed70e8a59d6439b2122190f'
        '0ade04ee0ae89d1168792a65c28956557c9f2991d141180b9faf7a9ae986cf24'
      2025-05-31T10:30:50.837000Z TestFramework (INFO): Stopping nodes

  While underlying error is `bad-cbtx-invalid-clsig`:

       2025-05-31T10:28:49.932591Z [util/system.h:57] [error] ERROR: ConnectBlock(DASH): ProcessSpecialTxsInBlock for block 4f8767d0ad2e7c8882ba4b2819a1d8eb29fbc608ff8201ed1c857d6d3ec51cc9 failed with bad-cbtx-invalid-clsig
       2025-05-31T10:28:49.932632Z [validationinterface.cpp:254] [BlockChecked] [validation] BlockChecked: block hash=4f8767d0ad2e7c8882ba4b2819a1d8eb29fbc608ff8201ed1c857d6d3ec51cc9 state=bad-cbtx-invalid-clsig
       2025-05-31T10:28:49.932660Z [validation.cpp:1634] [InvalidChainFound] InvalidChainFound: invalid block=4f8767d0ad2e7c8882ba4b2819a1d8eb29fbc608ff8201ed1c857d6d3ec51cc9  height=202  log2_work=8.665336  date=2014-12-04T17:46:38Z
       2025-05-31T10:28:49.932667Z [validation.cpp:1639] [InvalidChainFound] InvalidChainFound:  current best=0ade04ee0ae89d1168792a65c28956557c9f2991d141180b9faf7a9ae986cf24  height=201  log2_work=8.658211  date=2014-12-04T17:36:30Z

  ## What was done?
  Chainlocks in CbTx can be only in Basic scheme.
  This PR splits activation of v19 and v20 to different blocks and wait until the best chainlocks will be formed in BASIC scheme.

  ## How Has This Been Tested?
  Run functional test `feature_dip3_v19.py` multiple times.

  ## Breaking Changes
  On RegTest `v20` is enforced to be activated after v19. In practice, any chainlocks in CbTx formed without v19 activated will stop the chain.  Added assert for `regtest` to be sure that combination of various `-testactivationheight` won't stop chain

  ## Checklist:
  - [x] I have performed a self-review of my own code
  - [x] I have commented my code, particularly in hard-to-understand areas
  - [x] I have added or updated relevant unit/integration/functional/e2e tests
  - [ ] I have made corresponding changes to the documentation
  - [x] I have assigned this pull request to a milestone

ACKs for top commit:
  UdjinM6:
    utACK d1e820f
  PastaPastaPasta:
    utACK d1e820f

Tree-SHA512: 6e5e468f783341a9ef4f6946bdab996b96f0e1de1cb0cfc6dabd62300bf334c9184a862aa5bd151677f595fd0cf85f6190c673e5ddd17d15254f9737270dfb7e

Author: PastaPastaPasta

src/chainparams.cpp

@@ -925,7 +925,9 @@ class CRegTestParams : public CChainParams {
         UpdateLLMQTestParametersFromArgs(args, Consensus::LLMQType::LLMQ_TEST_INSTANTSEND);
         UpdateLLMQTestParametersFromArgs(args, Consensus::LLMQType::LLMQ_TEST_PLATFORM);
         UpdateLLMQInstantSendDIP0024FromArgs(args);
+        // V20 features for CbTx (credit pool, CL) have no meaning without masternodes
         assert(consensus.V20Height >= consensus.DIP0003Height);
+        // MN_RR reallocate part of reward to CreditPool which exits since V20
         assert(consensus.MN_RRHeight >= consensus.V20Height);
     }
 

src/evo/cbtx.cpp

@@ -392,6 +392,10 @@ bool CalcCbTxBestChainlock(const llmq::CChainLocksHandler& chainlock_handler, co
                            uint32_t& bestCLHeightDiff, CBLSSignature& bestCLSignature)
 {
     auto best_clsig = chainlock_handler.GetBestChainLock();
+    if (best_clsig.getHeight() < Params().GetConsensus().DeploymentHeight(Consensus::DEPLOYMENT_V19)) {
+        // We don't want legacy BLS ChainLocks in CbTx (can happen on regtest/devenets)
+        best_clsig = llmq::CChainLockSig{};
+    }
     if (best_clsig.getHeight() == pindexPrev->nHeight) {
         // Our best CL is the newest one possible
         bestCLHeightDiff = 0;

src/test/evo_deterministicmns_tests.cpp

@@ -866,7 +866,7 @@ struct TestChainV19Setup : public TestChainV19BeforeActivationSetup {
 
 // 5 blocks earlier
 TestChainV19BeforeActivationSetup::TestChainV19BeforeActivationSetup() :
-    TestChainSetup(494, {"-testactivationheight=v19@500"})
+    TestChainSetup(494, {"-testactivationheight=v19@500", "-testactivationheight=v20@500", "-testactivationheight=mn_rr@500"})
 {
     bool v19_active{DeploymentActiveAfter(m_node.chainman->ActiveChain().Tip(), Params().GetConsensus(),
                                           Consensus::DEPLOYMENT_V19)};

src/test/util/setup_common.cpp

@@ -399,7 +399,7 @@ TestChainSetup::TestChainSetup(int num_blocks, const std::vector<const char*>& e
             /*TestChainBRRBeforeActivationSetup=*/
             {  497, uint256S("0x0857a9b5db51835b1c828f019f4c664b5fe6c28ac44a6d868436930f832d31e5") },
             /*TestChainV19BeforeActivationSetup=*/
-            {  494, uint256S("0x06ec12cb5419daf83e04455a24ff8f27fef76cfdbd3e8723ca4946fab91a2f11") },
+            {  494, uint256S("0x44ee5c8a5e5cbd4437d63c54ddc1d40329be811b25c492fa901e11cdf408f905") },
         }
     };