[web/json] an empty rset is just fine for ejsonexport
The ejsonexport view can just return an empty list for an empty rset.
Closes #4005518
#! /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