SERVER-39158 added the requirement that to update the value of a document's shard key, the update's query must include an equality match on the full shard key. SERVER-42390 changed the treatment of missing shard key fields when targeting based on a user document (e.g. a replacement document in an update) but incorrectly removed the restriction that the full shard key must be present in a query to update a shard key value. This requirement should be added back.