Depends on 

There are a lot of different orderings of events, listed here. We decided that it would be best to test these with the mocking implementation. 

Test cases to add under this ticket (additional ones covered under sub-task) :

• The authoritative read fails first with an ignorable error, and the hedged read is cancelled. The counters show: succeeded: 1 and canceled: 1. The ignorable error is seen as the response.
• The authoritative read fails with a fatal error, and the hedged read is cancelled. The counters show success: 1 and canceled: 1. The fatal error is shown as the response.
• The authoritative read succeeds, and the hedged read is cancelled. The counters show success: 1 and failed: 0 and canceled: 1. The success is shown as the response.
• The hedged read succeeds, and the authoritative request is canceled. The counters show success: 1 and canceled: 1. The success is shown as the response.