test: Remove unused imports

test/functional/rpc_invalidateblock.py

@@ -1,5 +1,5 @@
 #!/usr/bin/env python3
-# Copyright (c) 2014-2018 The Bitcoin Core developers
+# Copyright (c) 2014-2019 The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 """Test the invalidateblock RPC."""
@@ -9,7 +9,6 @@ from test_framework.address import ADDRESS_BCRT1_UNSPENDABLE
 from test_framework.util import (
     assert_equal,
     connect_nodes_bi,
-    sync_blocks,
     wait_until,
 )