message: Add syncronisation point to wallet.py when doing maintenance tests
  With all our multi-threading we need to make sure the blockchain is
  fully restarted during all maintenance tests , not just -reindex, and
  before we do an testing for asserts.
diff: @@ -446,9 +446,7 @@ class WalletTest (BitcoinTestFramework):
  wait_bitcoinds()
  self.node_args = [['-usehd=0', m], ['-usehd=0', m], ['-usehd=0', m]]
  self.nodes = start_nodes(3, self.options.tmpdir, self.node_args)
  - while m == '-reindex' and [block_count] * 3 != [self.nodes[i].getblockcount() for i in range(3)]:
  - # reindex will leave rpc warm up "early"; Wait for it to finish
  - time.sleep(0.1)
  + waitFor(60, lambda : [block_count] * 3 == [self.nodes[i].getblockcount() for i in range(3)])
  assert_equal(balance_nodes, [self.nodes[i].getbalance() for i in range(3)])
  # Exercise listsinceblock with the last two blocks
  