[rql / querier] fix bad interpretation of some RQL SET query
when some neged relation is involved. Closes #3058527.
#! /bin/sh -e#if [ "$1" = configure ]; then if which install-docs >/dev/null 2>&1; then install-docs -i /usr/share/doc-base/cubicweb-doc fifi#DEBHELPER#exit 0