cro test irregularly fail on macOS

[vrurg]

macOS 10.13
This is Rakudo version 2018.08 built on MoarVM version 2018.08 (installed with rakudobrew)

t/tools-runner.t fails with the following output:

===> Testing: cro:ver<0.7.6>
# Check service up attempt 1: connection refused
# Check service up attempt 2: connection refused
# Check service up attempt 3: connection refused
# Check service up attempt 4: connection refused
# Check service up attempt 5: connection refused
# Check service up attempt 6: connection refused
# Check service up attempt 7: connection refused
# Check service up attempt 8: connection refused
# Check service up attempt 9: connection refused
# Check service up attempt 10: connection refused
# Check service up attempt 11: connection refused
# Check service up attempt 12: connection refused
# Failed test 'Got response indicating new service running'
# at t/tools-runner.t line 81
# expected: 'Service 1 UPDATED'
#      got: 'Service 1 OK'
# Looks like you failed 1 test of 20

Failure is irregular though it passes in about 1 time out of 5-7 attempts.