bug#52520: Multicast is off by default

[Mathieu Othacehe]

Hey,

> BTW, for the purposes of fixing the bug you initially reported, I
> suggest simply adding #:multicast-on #t as you initially proposed.
> We discuss the proper API separately.

Done with: d2f9578a9f1249dfecb0a6b4cd06fd9641fcd1a9.

Thanks,

Mathieu