[server] extract "no pooler" CnxSet class to a _BaseCnxSet class So we get rid of "if self._queue is None" in each method of _CnxSetPool Also add helper get_cnxset(source, size) to instantiate the correct pooler class.

%(distname)s (0.1.0-1) UNRELEASED; urgency=medium

  * Initial release.

 -- %(author)s <%(author-email)s>  %(rfc2822-date)s