Don't exhaust the connection pool when listing repos.
Don't exhaust the connection pool when listing repos.

Reuse the DataHubManager in DataHubSerializer subclasses.

Also, use `except Exception:` instead of `except:` to make things easier to debug, since `except:` will consume KeyboardInterrupt, StopIteration, GeneratorExit, and SystemExit.

anantb/datahub,datahuborg/datahub,RogerTangos/datahub-stub,RogerTangos/datahub-stub,anantb/datahub,anantb/datahub,RogerTangos/datahub-stub,anantb/datahub,RogerTangos/datahub-stub,datahuborg/datahub,RogerTangos/datahub-stub,RogerTangos/datahub-stub,anantb/datahub,datahuborg/datahub,datahuborg/datahub,datahuborg/datahub,datahuborg/datahub,anantb/datahub,datahuborg/datahub,RogerTangos/datahub-stub,anantb/datahub