x/net/ipv4: TestPacketConnReadWriteMulticastUDP failures with `i/o timeout`

[gopherbot]

#!watchflakes
post <- pkg == "golang.org/x/net/ipv4" && test == "TestPacketConnReadWriteMulticastUDP" && `i/o timeout`

Issue created automatically to collect these failures.

Example (log):

--- FAIL: TestPacketConnReadWriteMulticastUDP (0.85s)
    --- FAIL: TestPacketConnReadWriteMulticastUDP/addr=232.0.1.0:0/grp=232.0.1.254/src=127.0.0.1 (0.70s)
        multicast_test.go:117: read udp 0.0.0.0:29306: raw-read udp4 0.0.0.0:29306: i/o timeout

— watchflakes

[gopherbot]

Found new dashboard test flakes for:

#!watchflakes
post <- pkg == "golang.org/x/net/ipv4" && test == "TestPacketConnReadWriteMulticastUDP"

2023-03-09 22:21 freebsd-arm-paulzhol net@9f24bb44 go@5f62ba62 x/net/ipv4.TestPacketConnReadWriteMulticastUDP (log)

--- FAIL: TestPacketConnReadWriteMulticastUDP (0.85s)
    --- FAIL: TestPacketConnReadWriteMulticastUDP/addr=232.0.1.0:0/grp=232.0.1.254/src=127.0.0.1 (0.70s)
        multicast_test.go:117: read udp 0.0.0.0:29306: raw-read udp4 0.0.0.0:29306: i/o timeout

— watchflakes

[bcmills]

See also #57842.