pyflakes cleanups to RPC tests after Overwinter PRs.

Signed-off-by: Daira Hopwood <daira@jacaranda.org>

qa/rpc-tests/mempool_tx_expiry.py

@@ -8,13 +8,11 @@
 #
 
 from test_framework.test_framework import BitcoinTestFramework
-from test_framework.authproxy import JSONRPCException
-from test_framework.util import assert_equal, connect_nodes, \
-    connect_nodes_bi, sync_blocks, start_nodes, sync_blocks, sync_mempools, \
+from test_framework.util import assert_equal, \
+    connect_nodes_bi, sync_blocks, start_nodes, \
     wait_and_assert_operationid_status
 
 from decimal import Decimal
-import time
 
 class MempoolTxExpiryTest(BitcoinTestFramework):
 
@@ -25,17 +23,16 @@ class MempoolTxExpiryTest(BitcoinTestFramework):
     # TODO: Test case of dependent txs in reorgs
     # chain is at block height 199 when run_test executes
     def run_test(self):
-        alice = self.nodes[0].getnewaddress()
         z_alice = self.nodes[0].z_getnewaddress()
         bob = self.nodes[2].getnewaddress()
         z_bob = self.nodes[2].z_getnewaddress()
-        
+
         # When Overwinter not yet activated, no expiryheight in tx
         sapling_tx = self.nodes[0].sendtoaddress(bob, 0.01)
         rawtx = self.nodes[0].getrawtransaction(sapling_tx, 1)
         assert_equal(rawtx["overwintered"], False)
         assert("expiryheight" not in rawtx)
-        
+
         self.nodes[0].generate(6)
         self.sync_all()