gitlab-ci-multi-runner using Windows Container on Windows Server 2016 TP5

Hi, so I'm trying to use the new Windows Containers on the Windows Server 2016 TP5 running as Windows Server Core and running a docker image called win-py2.7. Docker is setup in a way that the server use the docker engin and not a docker-machine configured using the classic boot2docker.iso. I achieved this using the microsoft provided bootstrapping script (see my comment to this issue for details).

The docker engin is

PS C:\> docker version
Client:
 Version:      1.12.0-dev
 API version:  1.24
 Go version:   go1.5.3
 Git commit:   2b97201
 Built:        Tue Apr 26 23:51:36 2016
 OS/Arch:      windows/amd64

Server:
 Version:      1.12.0-dev
 API version:  1.24
 Go version:   go1.5.3
 Git commit:   2b97201
 Built:        Tue Apr 26 23:51:36 2016
 OS/Arch:      windows/amd64

I also have the following docker container (please don't laugh at the 10GB container, that's how microsoft ship it).

C:\Multi-Runner>docker images
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
win-py2.7           latest              3c9daa366425        21 hours ago        10.22 GB
nanoserver          10.0.14300.1010     cb48429c84fa        6 weeks ago         817.1 MB
nanoserver          latest              cb48429c84fa        6 weeks ago         817.1 MB
windowsservercore   10.0.14300.1000     dbfee88ee9fd        6 weeks ago         9.344 GB
windowsservercore   latest              dbfee88ee9fd        6 weeks ago         9.344 GB

Using the following .gitlab-ci.yml I run a build

stages:
  - test

run_linux:
  image: el6.7-py2.7:latest
  before_script:
    - pip install setuptools
    - pip install tox
    - pip install coveralls
  stage: test
  tags:
    - linux
  variables:
    PYTHONPATH: ./
  script:
    - python2.7 setup.py test
  only:
    - master

run_windows:
  image: win-py2.7:latest
  stage: test
  tags:
    - windows
  variables:
    PYTHONPATH: ./
    PYTHONIOENCODING: utf-8
  script:
    - python setup.py test
  only:
    - master

But I get the following error message for the run_windows job (the run_linux job run flawlessly):

gitlab-ci-multi-runner 1.1.3 (a470667)
Using Docker executor with image win-py2.7:latest ...
ERROR: Failed to create container volume for /cache Get http://unix.sock/v1.18/version: dial unix /var/run/docker.sock: socket: An address incompatible with the requested protocol was used.
ERROR: Failed to create container volume for /builds/root Get http://unix.sock/v1.18/version: dial unix /var/run/docker.sock: socket: An address incompatible with the requested protocol was used.

ERROR: Build failed: Get http://unix.sock/v1.18/version: dial unix /var/run/docker.sock: socket: An address incompatible with the requested protocol was used.

If I disable the cache, I get:

ERROR: Build failed: Get http://unix.sock/v1.18/version: dial unix /var/run/docker.sock: socket: An address incompatible with the requested protocol was used.

Here's my runner's config.toml

concurrent = 1

[[runners]]
  name = "Windows Server 2016 TP5"
  url = "http://192.168.56.103/ci"
  token = "f30d953facad801c3e633220584bec"
  executor = "docker"
  [runners.docker]
    tls_verify = false
    image = "windowsservercore"
    privileged = false
    disable_cache = true
    volumes = ["/cache"]
  [runners.cache]
    Insecure = false

There's a way to tell the runner to use windows socket instead of linux socket?