- Reworking of _cached_result in Shared.DC.ZRDB.DA.DA:

        - fixed KeyError reported in Collector #2212

        - fixed two memory leaks that occurred under high load

        - fixed broken cache keys for people using the obscure 
          Shared.DC.ZRDB.DA.DA.connection_hook

        - fixed incorrect cache ordering resulting in newer results
          being dumped when the cache became too large.