fix test_fail_pending_htlcs_on_shutdown: poll number of htlcs
fix test_fail_pending_htlcs_on_shutdown: poll number of htlcs

pooler/electrum-ltc,spesmilo/electrum,spesmilo/electrum,pooler/electrum-ltc,spesmilo/electrum,pooler/electrum-ltc,pooler/electrum-ltc,spesmilo/electrum