Because we need to allow for a smooth upgrade from Ocata to
Pike, we need Pike compute hosts to be tolerant of the bad accounting
assumptions that Ocata compute hosts were making. If a user migrates an
instance from an Ocata compute host to a Pike compute host, the Ocata
compute host will continue essentially re-setting the instance
allocation to be an allocation against only the source Ocata host
(during the migration operation). We need to have the Pike destination
compute host recognize when its in a mixed Ocata/Pike environment and
tolerate this incorrect "healing" that the Ocata source host will do.
To tolerate this, the Pike destination compute host must continue to
behave like an Ocata compute host until all compute hosts are upgraded
to Pike or beyond.
Note that this adds service version caching for the compute service.
We were already doing the lookup for the RPC pin and caching that,
so this is not much of a change. Also note that we weren't clearing
this caching in tests, so any test that ran code that cached the
service version would affect later ones. This clears it as part of the
base test setup too.
Co-Authored-By: Jay Pipes <firstname.lastname@example.org>