Noticed a bug in C Driver's updateRSWithPrimaryFromMember that wasn't
revealed by any SDAM test:

1. Discover primary, topology type is ReplicaSetWithPrimary
2. In next ismaster response from primary it has become secondary *and*
   changed setName

Expected: server removed, topology type changes to ReplicaSetNoPrimary

Actual: server removed but topology type remains ReplicaSetWithPrimary