system test fails on single stack system

system test fails on single stack system:

I:resolver:check that the resolver limits the number of NS records it follows in a referral response (28)
I:resolver:query count error: 1 NS records: expected queries 2, actual 1
I:resolver:query count error: 2 NS records: expected queries 4, actual 2
I:resolver:query count error: 3 NS records: expected queries 6, actual 3
I:resolver:query count error: 4 NS records: expected queries 8, actual 4
I:resolver:query count error: 5 NS records: expected queries 10, actual 5
I:resolver:query count error: 6 NS records: expected queries 10, actual 5
I:resolver:query count error: 7 NS records: expected queries 10, actual 5
I:resolver:query count error: 8 NS records: expected queries 10, actual 5
I:resolver:query count error: 9 NS records: expected queries 10, actual 5
I:resolver:query count error: 10 NS records: expected queries 10, actual 5

RT #16496