query-head fix source reporting

QueryHead will return what sources have been attempted in the query result. The current implementation will not actually update the list of attempted sources when an new attempt is made that is outdated. It will only update the list of attempted sources when a new source was attempted that actually has newer data. This surfaces as an issue in the case where the network actually beats the disk with the latest data, and a query is dependent on knowing that the latest value from disk has been queried. Due to this a new message forever waits to be published waiting on the latest disk value to know the current head.