If the sync source is in the replica set config, but not in state PRIMARY or SECONDARY, we issue a retryable error, causing us to retry connecting until the node is in state PRIMARY or SECONDARY. This is a liveness issue if the sync source is in initial sync, since it could take a long time for the sync source to finish initial sync. It's also a correctness issue, since the sync source can be on a different branch of history when it completes its initial sync. We should fail the initial sync attempt if the sync source is in initial sync.