[toward py3k] rewrite has_key() (part of #2711624)
The `has_key` method is not in Python3K but dict supports __contains__ check for
ages.
#! /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