Queries fail during shard creation [testcase included]

Shard creation takes a certain amount of time. Queries launched between the start of shard creation and the full "upness" of the shard will fail: "Error from server at foo: no servers hosting shard: bar".

Ideally, shards should not be used in queries before their creation is fully completed. A new shard is empty anyway, so its upness couldn't even influence the query results in any way.

I'm attaching a testcase which reproduces the problem. Tested on two machines, but your mileage may vary assuming this is a concurrency issue.