On my test machine, we queried bitcoind before the close tx was sent:
```
# When output is spent, it should give us null !
txo = l1.rpc.call("getutxout", {"txid": txid, "vout": 0})
> assert txo["amount"] is txo["script"] is None
E AssertionError: assert '20000000msat' is '00205b8cd3b914cf67cdd8fa6273c930353dd36476734fbd962102c2df53b90880cd'
tests/test_plugin.py:1221: AssertionError
```
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2f4c16c388