[predicates] fix 'adaptable' implementation, used to return 0 on a rset with individualy adaptable entities of different types. Closes #2709663
#! /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