If a config shard is being added (i.e the shard id == "config"), then this check that the CWWC on the shard equals the CWWC on the config can be skipped. The check is redundant because they are the same for a config shard.

Leaving the check in for a config shard can also result in the following race condition:

1. The value of cwwcOnShard is w:1
2. Before cwwcOnConfig is also set to w:1 here, the cwwc on the config server is changed to w:majority 
3. Then when the cwwcOnConfig is actually set, it is set to w:majority, resulting in this check to fail.