Ideally we'd 'cure' the error and re-attempt, except that if this was a
bitcoin-backend 'failure to broadcast' then it really needs user
intervention to figure out what's wrong -- it's possible that the
peer successfully broadcast the transaction
Any file in this directory which is executable and whose name only
consists of alphanumeric characters, space, '.', '-' or '_' will be
automatically loaded when lightningd starts (unless suppressed with
commandline options).