dns.query.UnexpectedSource: got a response from ('10.53.0.6', 7279) instead of ('10.53.0.3', 7559)

The shutdown system test of the system:gcc:bookworm:amd64 job on the main-PRE-RELEASE branch (main + isc-private/bind9!732) failed with:

_________________________ test_named_shutdown[sigterm] _________________________
[gw3] linux -- Python 3.11.2 /usr/bin/python3
/builds/isc-private/bind9/bin/tests/system/shutdown/tests_shutdown.py:172: in test_named_shutdown
    do_work(
/builds/isc-private/bind9/bin/tests/system/shutdown/tests_shutdown.py:119: in do_work
    result = future.result()
/usr/lib/python3.11/concurrent/futures/_base.py:449: in result
    return self.__get_result()
/usr/lib/python3.11/concurrent/futures/_base.py:401: in __get_result
    raise self._exception
/usr/lib/python3.11/concurrent/futures/thread.py:58: in run
    result = self.fn(*self.args, **self.kwargs)
/builds/isc-private/bind9/bin/tests/system/isctest/query.py:55: in udp
    return generic_query(dns.query.udp, *args, **kwargs)
/builds/isc-private/bind9/bin/tests/system/isctest/query.py:45: in generic_query
    res = query_func(message, ip, timeout, port=port, source=source)
/usr/lib/python3/dist-packages/dns/query.py:647: in udp
    (r, received_time) = receive_udp(
/usr/lib/python3/dist-packages/dns/query.py:566: in receive_udp
    if _matches_destination(
/usr/lib/python3/dist-packages/dns/query.py:208: in _matches_destination
    raise UnexpectedSource(
E   dns.query.UnexpectedSource: got a response from ('10.53.0.6', 7279) instead of ('10.53.0.3', 7559)

Curiously, this is after the slight !9150 (merged) refactorings; tho, that did not change the logic of the test; this happened for the first time; I can't reproduce it locally on the same branch and image.

Hopefully, this is just a spillover from another test running in parallel like we used to have (see !8698 (merged)).

• Close in a month if it's not a common issue