Ephemeral data store intermittently returns stale data

[cammoore]

Reported by rbrewer, Sep 4, 2012
The ephemeral data storage system seems to sometimes return old data for latest sensor data calls. This can be reproduced by looking at the latest sensor data for a source that is being frequently updated, and reloading the page frequently. After a few reloads, the returned timestamp will be older than the previous reload.

This happens for both virtual and non-virtual sources.