Wait for connection to open in bip9-softforks.py

bip9-sofforks.py stop-starts the bitcoind node twice during the test
run, but it doesn't wait for the connection from mininode to open before
continuing with the test. This leads to race conditions where the test
can fail getblocktemplate() because it has no p2p connections.

test/functional/bip9-softforks.py

@@ -200,16 +200,14 @@ class BIP9SoftForksTest(ComparisonTestFramework):
         yield TestInstance([[block, False]])
 
         # Restart all
-        self.test.block_store.close()
+        self.test.clear_all_connections()
         stop_nodes(self.nodes)
-        shutil.rmtree(self.options.tmpdir)
+        shutil.rmtree(self.options.tmpdir + "/node0")
         self.setup_chain()
         self.setup_network()
-        self.test.block_store = BlockStore(self.options.tmpdir)
-        self.test.clear_all_connections()
         self.test.add_all_connections(self.nodes)
-        NetworkThread().start() # Start up network handling in another thread
-
+        NetworkThread().start()
+        self.test.test_nodes[0].wait_for_verack()
 
     def get_tests(self):
         for test in itertools.chain(