Pierre-Yves David <pierre-yves.david@logilab.fr> [Wed, 26 Jun 2013 14:01:07 +0200] rev 9105
[session] explicitly take Connection object in close_cnx
Now that ClientConnection explicitly reference and use the Connection object we
do not need to use connectionid here.
We can safely change this signature, ClientConnection is the only use of
close_cnx for now.