Setup: 2 mongos, 2 shards.

1. movePrimary sent to mongos1.
2. movePrimary changed primary from shardA to shardB
3. send insert to mongos1.
4. send count to mongos2. Mongos2 still sees state before movePrimary and routes count to shardA.
5. shard does not reject count since version matches (0,0|0) matches (0,0|0)
6. counts shows 0 documents.