SERVER-30025 will make the scatterGather*() methods throw a StaleConfigException on seeing a stale shardVersion error in a response from a shard.

This StaleConfigException is caught at the top of mongos in generic command processing, and the command gets retried from the beginning.

So, a command need not intercept stale shardVersion errors and perform any complicated retry logic itself.

This will fix a bug in aggregation, where if a sharded collection is dropped and recreated as a view, the view definition response was not handled by the aggregation code on mongos.