The existing test_GET_sharded_container_gap_in_shards does not set
memcache in the request environ and therefore does not exercise the
proxy container controller code path for caching fetched shard ranges.
This patch add two new tests:
- test_GET_sharded_container_gap_in_shards_memcache which is similar
to the existing but sets memcache in the request environ so that
the fetched shard ranges (with gaps) are cached by the controller.
- test_GET_sharding_container_gap_in_shards_memcache which sets
memcache in the request environ but has the root pretend to be in
sharding state so that the fetched shard ranges (with gaps) are
not cached by the controller.
In all cases the pretend root response headers are fixed to include
'X-Backend-Override-Shard-Name-Filter': 'true', which the real
container server would return. This is another precondition for shard
ranges being cached by the controller.
Change-Id: I1f13690174cc2bddeca152a87cc978dee2a136d6
9a1bfb8975