I noticed the Commitment Transaction Output script is weak to malleability,
this can be used to delay confirmation of the revocation.
Luckily, fixing the situation does not require lots of development.
```
OP_IF
# Penalty transaction
OP_ELSE
`to_self_delay`
OP_CSV
OP_DROP
Actually this was merged as policy rules in 0.14, not 0.15.1.
Not as bad as I thought, but still a bit uneasy about someone malleating my
transaction.
Another way to fix the situation which would not require the BOLT to change
is to enable RBF of the Penalty transaction so Eve transaction would