[views] fix ProcessInformationView: SESSION_MANAGER can be None (closes #5753280)
eg. with pyramid.
(grafted from 6a07c2dc3d85f4de0cf48221607e02c4473e11e4)
#! /bin/sh -ecase "$1" in remove) if [ -x "/etc/init.d/cubicweb-ctl" ]; then invoke-rc.d cubicweb-ctl stop || true fi ;;esac#DEBHELPER#exit 0