We don't care much about outgoing for Heptapod (yet still, it could
turn out to be useful for command-line debugging).

As a funny thing, the work done in 76d1ceaf8886 affects also
`outgoing`, that's not a problem, but we have to adapt the tests.

Also making sure the warning ends in LF, for cases where it ends
up in console, and not in `logging`.