[repo] ensure we don't restart a task while the repo is shutting down (closes #1942736) we need a safety belt in cw itself again looping task which use 'try / except' or doesn't need to access the db (which will trigger ShuttingDown exception)

#!/bin/sh -e
if [ "$1" = "purge" ] ; then
        update-rc.d cubicweb remove >/dev/null
fi
 
#DEBHELPER#
 
exit 0