Broken subscription test

[coot]

Broken test on X86_64-darwin

    Resolve Subscribe (IO):                                    FAIL (1.64s)
      *** Failed! Falsified (after 33 tests):
      LookupResultIO: ipv4: Right [3,1] ipv6: Left RetryLimitExceeded first AF_INET valency 8
      [3,1] /= [1,3]
      Use --quickcheck-replay=899773 to reproduce.
      Use -p '/Resolve Subscribe (IO)/' to rerun this test only.

ref on #4846.

I wasn't able to reproduce it on Linux.