message: test: use 327 fewer blocks in feature_nulldummy
  by generating 100 blocks for coinbase maturity instead of 427.
  This speeds up the test and should help avoid timeout errors.
diff: @@ -20,14 +20,14 @@ from test_framework.script import CScript
  from test_framework.test_framework import BitcoinTestFramework
  from test_framework.util import assert_equal, assert_raises_rpc_error
  -COINBASE_MATURITY = 427
  +COINBASE_MATURITY = 100
  NULLDUMMY_ERROR = "non-mandatory-script-verify-flag (Dummy CHECKMULTISIG argument must be zero)"
  def trueDummy(tx):
  scriptSig = CScript(tx.vin[0].scriptSig)
  newscript = []
  for i in scriptSig:
  - if (len(newscript) == 0):
  + if len(newscript) == 0:
  assert len(i) == 0
  newscript.append(b'\x51')
  else:
  @@ -38,7 +38,7 @@ def trueDummy(tx):
  class NULLDUMMYTest(BitcoinTestFramework):
  def set_test_params(self):
  - # Need two nodes only so GBT doesn't complain that it's not connected
  + # Need two nodes so GBT (getblocktemplate) doesn't complain that it's not connected.
  self.num_nodes = 2
  self.setup_clean_chain = True
  # This script tests NULLDUMMY activation, which is part of the 'segwit' deployment, so we go through
  