test: Fix intermittent error in mempool_reorg
test: Fix intermittent error in mempool_reorg

Former-commit-id: fce98faeec8cb70b45b66c96ae0445acd32462a3
syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin