[migration] fix bug in `CWAttributeAddOp.revertprecommit_event` The `rdefdef` attribute is set during the operation execution. In some the operation crash before this assignment. In such case `revertprecommit` raise an attribute error crashing the whole process and shadowing the original error. This changeset detect and Avoid this situation.

#! /bin/sh -e

if [ -x "/etc/init.d/cubicweb-ctl" ]; then
    invoke-rc.d cubicweb-ctl restart || true
fi
 
 
#DEBHELPER#
 
exit 0