The test `p2p_private_broadcast.py` gets some Python P2P nodes to listen
and instructs the SOCKS5 proxy to redirect connections to them instead
of to the requested addresses. This way the `bitcoind` which uses the
proxy is tricked to think it has connected to real routable internet
IP addresses or `.onion` addresses.
Picking the ports where to Python P2P nodes to listen however is tricky
to be done in a non-conflicting way, given that other tests may run in
parallel. https://github.com/bitcoin/bitcoin/pull/34186 made it possible
to let the OS select a free port, so use that in
`p2p_private_broadcast.py`.
w0xlt