In refine_collection_shard_key_basic.js, we refine the shard key and then wait for the shards to discover the new collection epoch.
In absence of a mongoS that discovers the new epoch and then queries the shards with that shardVersion, the shard would only discover the new epoch through this best-effort refresh triggered at the end of _configsvrRefineCollectionShardKey. In stepdown suites, this refresh might fail.

refine_collection_shard_key_basic.js should either:
1. Not test this particular condition (at least, on stepdown suites)
2. Ensure that the shards discover the new shard version by having a mongos first see it and having it query the shards with it.