pytest: fix feerate check in test_peer_anchor_push
We didn't log when anchor transactions had short signatures,
which causes this test to not assert (did_short_sig):
```
total_feerate_perkw = total_fees / total_weight * 1000
> check_feerate([l3, l2], total_feerate_perkw, feerate)
tests/test_closing.py:4063:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
nodes = [<fixtures.LightningNode object at 0x7f0fb322bb20>, <fixtures.LightningNode object at 0x7f0fb1b5ead0>]
actual_feerate = 14006.105538595726, expected_feerate = 14000
def check_feerate(nodes, actual_feerate, expected_feerate):
# Feerate can't be lower.
assert actual_feerate > expected_feerate - 2
if actual_feerate >= expected_feerate + 2:
if any([did_short_sig(n) for n in nodes]):
return
# Use assert as it shows the actual values on failure
> assert actual_feerate < expected_feerate + 2
E AssertionError
```
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
8a60a27662