contrib/docker/debian-jessie

merge: drop redundant column in docstring table

The "same" and "cross" columns now have the same values, so let's
combine them into "non-linear".

FROM debian:jessie
RUN apt-get update && apt-get install -y \
  build-essential \
  debhelper \
  dh-python \
  devscripts \
  python \
  python-all-dev \
  python-docutils \
  zip \
  unzip