replicaset: rework the test to not start two mongodb replicas during the IPV6 test
Merge pull request #379 from davecheney/153-make-replicaset-tests-a-little-less-wasteful

replicaset: rework the test to not start two mongodb replicas during the IPV6 test

Doesn't fix the problem with the test, but tries to isolate the failing part a little better.