[server] use a LifoQueue in _CnxSetPool
In postgresql, some cache is attached to the connection. Using a LifoQueue
(last-in, first-out) makes a few connections to get the most load which give
best performance.
.. _session_module:
:mod:`cubicweb.pyramid.session`
-------------------------------
.. automodule:: cubicweb.pyramid.session
.. autofunction:: includeme
.. autofunction:: CWSessionFactory