contrib/docker/debian-jessie

py3: provide encoding.environ which is a dict of bytes

This can't be moved to pycompat.py since we need encoding.tolocal() to
build bytes dict from unicode os.environ.

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