4.1.0 kept a fresh socket for a dial to one of the host's own listeners,
but it compared only the port number. A dial to a remote peer that
listens on the same port number, as nodes on a fixed port all do, still
left from an ephemeral socket, and that peer observed an address that
leads nowhere.

A dial now counts as one to our own listener only for the listener's own
address, or, for a listener on all interfaces, for a loopback or
unspecified address with its port. go-libp2p-udx-transport v0.1.7 uses
the same rule.

Release 4.1.1.