Stale Documents Cache May Overwrite Itself In The Wrong Order

[anthonysharpy]

We store stale documents in a ConcurrentBag. However, we don't enforce that that same document is not stored twice. Not only that, but ConcurrentBag is unordered. So in really specific scenarios, an older version of a document may overwrite a newer version of a document when the stale documents are saved to disk. This is not really a big deal, as this would usually be overwritten again immediately by a correct version, but could cause issues in really really specific circumstances

[anthonysharpy]

This also arguably leads to performance issues, as it creates unnecessary writes