Once SERVER-39158 is done, replacement updates will target by query. We can then have a situation where a replacement upsert can target shard 1 using the query field, match 0 documents, and plan to insert the replacement document that actually belongs on shard 2.

i.e. If shard 1 owns [x: -infinity, x: 0) and shard 2 owns [x:0, x: +infinity) and there does NOT exist a document {x: -10}, then a user does db.coll.update({x: -10}, {x: 10}), we will target shard 1 and not match any documents. We will then insert {x: 10}, but this should be inserted on shard 2 and not on shard 1. We should instead throw WouldChangeOwningShard error so that mongos can start a transaction if not already in one and insert the document on the correct shard.