[pyramid] Get rid of a bare "except" in UpdateLoginTimeAuthenticationPolicy Also refactor a bit the method to restrict the try/except block to the code for which we actually want to catch an exception (i.e. the cnx.execute() + cnx.commit()).

#!/bin/sh -e

if [ "$1" = "purge" ] ; then
        rm -rf /etc/cubicweb.d/
        rm -rf /var/log/cubicweb/
        rm -rf /var/lib/cubicweb/
fi

#DEBHELPER#
 
exit 0