[test/tox] Enforce installation of modified yapps 580a6821713d is not enough for tox apparently... The thing is that it will first install dependencies (the `deps` option from tox.ini), actually pulling yapps from Logilab github but then, it will install the project (that is, CubicWeb) from the sdist *along with its dependencies*, which will pull yapps again and override the previously installed version for some mysterious reason. So add a `pip install` command in tox.ini, so that the modified yapps is the last one installed.

#! /bin/sh -e

case "$1" in
    configure|abort-upgrade|abort-remove|abort-deconfigure)
        update-rc.d cubicweb defaults 99 >/dev/null
    ;;
    *)
        echo "postinst called with unknown argument \`$1'" >&2
        exit 1
    ;;
esac

#DEBHELPER#

exit 0