The original design was to honour strong consistency
semantics for when the RV is unset, i.e. serve the
watch by doing a quorum read.
However, the implementation did not match the intent,
in that, the Cacher did not distinguish between set
and unset RV. This commit rectifies that behaviour by
serving the watch from the underlying storage if the
RV is unset.
This commit subsequently also adds a test for the same.
Signed-off-by: Madhav Jivrajani <madhav.jiv@gmail.com>
Kubernetes-commit: 610b67031c79c6c38964631d27dd59df357c6d2e
db00da87d8