Flaky test

[holiman]

https://ci.appveyor.com/project/ethereum/go-ethereum/builds/50672070/job/3vwt3vsbmg40vmi8#L1114

panic: Log in goroutine after TestUDPv4_LookupIterator has completed: TRACE[09-25|09:29:15.777] << PONG/v4                                id=d89f4c51d8efdaf0 addr=127.0.255.3:5000 err="unsolicited reply"
	
goroutine 36067 [running]:
testing.(*common).logDepth(0xc000116820, {0xc0017a5200, 0x86}, 0x3)
	C:/Users/appveyor/AppData/Local/geth-go-1.23.1-windows-amd64/go/src/testing/testing.go:1029 +0x4c5
testing.(*common).log(...)
	C:/Users/appveyor/AppData/Local/geth-go-1.23.1-windows-amd64/go/src/testing/testing.go:1011
testing.(*common).Logf(0xc000116820, {0x7ff77015f66e?, 0x7ff770400cc0?}, {0xc00055f2a8?, 0xa?, 0xfffffffffffffff8?})
	C:/Users/appveyor/AppData/Local/geth-go-1.23.1-windows-amd64/go/src/testing/testing.go:1062 +0x54
github.com/ethereum/go-ethereum/internal/testlog.(*logger).flush(0xc000643d70)
	C:/projects/go-ethereum/internal/testlog/testlog.go:211 +0x16d
github.com/ethereum/go-ethereum/internal/testlog.(*logger).Trace(0xc000643d70, {0xc0017cc530, 0xa}, {0xc0017b56e0, 0x6, 0x6})
	C:/projects/go-ethereum/internal/testlog/testlog.go:121 +0xd2
github.com/ethereum/go-ethereum/p2p/discover.(*UDPv4).handlePacket(0xc000f902d0, {{{0x0, 0xffff7f00ff03}, {0xc000008048}}, 0x1388}, {0xc001792fc0?, 0x60?, 0xc0017b8c30?})
	C:/projects/go-ethereum/p2p/discover/v4_udp.go:576 +0x4bd
github.com/ethereum/go-ethereum/p2p/discover.(*udpTest).packetInFrom(0xc0000e2690, {0x0, 0x0}, 0xc000025650, {{{0x1df7cde9200?, 0xc00179bd30?}, {0xc000008048?}}, 0x10?}, {0x7ff7701f7270, 0xc0017b5620})
	C:/projects/go-ethereum/p2p/discover/v4_udp_test.go:104 +0x245
github.com/ethereum/go-ethereum/p2p/discover.serveTestnet.func1({0x7ff7701f7248, 0xc0016a3ea0?}, {{{0xc0016a3ea0?, 0xc00055f788?}, {0xc000008048?}}, 0x3ae0?}, {0xc001792ee0, 0x20, 0xe0})
	C:/projects/go-ethereum/p2p/discover/v4_lookup_test.go:143 +0x29e
reflect.Value.call({0x7ff7700f69a0?, 0xc0017bca80?, 0x7ff76fdd123f?}, {0x7ff77015fb0c, 0x4}, {0xc00055ff40, 0x3, 0xc0017bcb10?})
	C:/Users/appveyor/AppData/Local/geth-go-1.23.1-windows-amd64/go/src/reflect/value.go:581 +0xca6
reflect.Value.Call({0x7ff7700f69a0?, 0xc0017bca80?, 0xe0?}, {0xc00055ff40?, 0xcda35b3d79bcd714?, 0xb6253f6da5a12b72?})
	C:/Users/appveyor/AppData/Local/geth-go-1.23.1-windows-amd64/go/src/reflect/value.go:365 +0xb9
github.com/ethereum/go-ethereum/p2p/discover.(*udpTest).waitPacketOut(0xc0000e2690, {0x7ff7700f69a0, 0xc0017bca80})
	C:/projects/go-ethereum/p2p/discover/v4_udp_test.go:132 +0x579
github.com/ethereum/go-ethereum/p2p/discover.serveTestnet(0xc0000e2690, 0x7ff7700c1e80)
	C:/projects/go-ethereum/p2p/discover/v4_lookup_test.go:139 +0x3c
created by github.com/ethereum/go-ethereum/p2p/discover.TestUDPv4_LookupIterator in goroutine 211
	C:/projects/go-ethereum/p2p/discover/v4_lookup_test.go:78 +0x2b5
FAIL	github.com/ethereum/go-ethereum/p2p/discover	112.864s

Fix inbound...