[migration] More resilient migration script
Query the information schema to retrieve existing constraint (primary key and
unique) and drop them.
Thus don't use anymore DROP CONSTRAINT IF EXISTS (not implemented by e.g. old
versions of sqlserver). To do so a missing DISTINCT was necessary to avoid
duplicates.
#! /bin/sh -e
if [ -x "/etc/init.d/cubicweb-ctl" ]; then
invoke-rc.d cubicweb-ctl restart || true
fi
#DEBHELPER#
exit 0