Bugfix: test/functional/mempool_accept: Ensure oversize transaction is actually oversize

Simply integer dividing results in an acceptable size if the limit isn't an exact multiple of the input size.
Use math.ceil to ensure the transaction is always oversize.

Author: luke-jr

test/functional/mempool_accept.py

@@ -5,6 +5,7 @@
 """Test mempool acceptance of raw transactions."""
 
 from io import BytesIO
+import math
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.messages import (
     BIP125_SEQUENCE_NUMBER,
@@ -178,7 +179,7 @@ def run_test(self):
 
         self.log.info('A really large transaction')
         tx.deserialize(BytesIO(hex_str_to_bytes(raw_tx_reference)))
-        tx.vin = [tx.vin[0]] * (MAX_BLOCK_BASE_SIZE // len(tx.vin[0].serialize()))
+        tx.vin = [tx.vin[0]] * math.ceil(MAX_BLOCK_BASE_SIZE / len(tx.vin[0].serialize()))
         self.check_mempool_result(
             result_expected=[{'txid': tx.rehash(), 'allowed': False, 'reject-reason': '16: bad-txns-oversize'}],
             rawtxs=[bytes_to_hex_str(tx.serialize())],