Use pip to install chutney's python dependencies

      if [ "$CHUTNEY" = yes ]; then

        git clone --depth 1 https://gitlab.torproject.org/tpo/core/chutney.git

        export CHUTNEY_PATH="$(pwd)/chutney"

        # Have pip install chutney's python dependencies by installing chutney

        # itself.

        apt-get install python3-pip

        pip3 install --user ./chutney

      fi

    - if [ "$TRACING" = yes ]; then apt install liblttng-ust-dev; fi