- The varnish controller deleted a service from its
map under the wrong conditions.

- Not an error if there are no Endpoints for the
Service when the Delete event is synced -- they
may already be gone.

- Varnish and haproxy controllers delete the service
from their maps before any other sync actions are
taken -- otherwise error returns may prevent the
deletion from ever happening.

- Permanent network errors on attempts to communicate
with the admin interfaces are ignored (do not cause
re-queue), since the instance may be gone.