qa: Avoid start/stop of the network thread mid-test

test/functional/p2p_invalid_block.py

@@ -14,7 +14,7 @@ import copy
 
 from test_framework.blocktools import create_block, create_coinbase, create_transaction
 from test_framework.messages import COIN
-from test_framework.mininode import network_thread_start, P2PDataStore
+from test_framework.mininode import P2PDataStore
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import assert_equal
 
@@ -28,8 +28,6 @@ class InvalidBlockRequestTest(BitcoinTestFramework):
         # Add p2p connection to node0
         node = self.nodes[0]  # convenience reference to the node
         node.add_p2p_connection(P2PDataStore())
-
-        network_thread_start()
         node.p2p.wait_for_verack()
 
         best_block = node.getblock(node.getbestblockhash())