message: Test txinwitness is accessible on coinbase vin
diff: @@ -20,6 +20,7 @@ from test_framework.script import CScript, OP_HASH160, OP_CHECKSIG, OP_0, hash16
  from test_framework.test_framework import BitcoinTestFramework
  from test_framework.util import (
  assert_equal,
  + assert_is_hex_string,
  assert_raises_rpc_error,
  connect_nodes,
  hex_str_to_bytes,
  @@ -188,6 +189,14 @@ class SegWitTest(BitcoinTestFramework):
  assert self.nodes[1].getrawtransaction(tx_id, False, blockhash) == self.nodes[2].gettransaction(tx_id)["hex"]
  assert self.nodes[0].getrawtransaction(tx_id, False, blockhash) == tx.serialize_without_witness().hex()
  + # Coinbase contains the witness commitment nonce, check that RPC shows us
  + coinbase_txid = self.nodes[2].getblock(blockhash)['tx'][0]
  + coinbase_tx = self.nodes[2].gettransaction(txid=coinbase_txid, verbose=True)
  + witnesses = coinbase_tx["decoded"]["vin"][0]["txinwitness"]
  + assert_equal(len(witnesses), 1)
  + assert_is_hex_string(witnesses[0])
  + assert_equal(witnesses[0], '00'*32)
  +
  self.log.info("Verify witness txs without witness data are invalid after the fork")
  self.fail_accept(self.nodes[2], 'non-mandatory-script-verify-flag (Witness program hash mismatch)', wit_ids[NODE_2][P2WPKH][2], sign=False)
  self.fail_accept(self.nodes[2], 'non-mandatory-script-verify-flag (Witness program was passed an empty witness)', wit_ids[NODE_2][P2WSH][2], sign=False)
  