Running while candidate in-flight quits successfully rather than raising an error

Change-Id: I6e602dbe801558e0a6cc66911500bd7a30fc6603
Reviewed-on: http://review.couchbase.org/33925
Reviewed-by: Chris Hillery <ceej@couchbase.com>
Tested-by: Chris Hillery <ceej@couchbase.com>