Trouble building the dockerfile

I'm on Windows 7 with docker 1.11

I've been trying to build with
docker build -t vpnkit .

I got this error:

I suspected that the path to the packages might be incorrect in the Dockerfile. So I changed this
RUN opam repo add dev /home/opam/src
to
RUN opam repo add dev /home/opam/src/opam/darwin

and it started complaining about . being an invalid token in the local directories. Based on the commit 54e7b199e02f7219204171a5cd0fa9334e45edc8, it seems like packages/local might only be needed for OSX.

So I removed them before adding the repo:
RUN sudo rm -rf /home/opam/src/opam/darwin/packages/local
RUN opam repo add dev /home/opam/src/opam/darwin

Everything seems to be building find, but I'm getting an error about topkg:

I tried a few things like adding a findlib to topkg in upstream but that didn't seem to work.

Do you have any ideas?

Start with the Dockerfile and reproduce docker build -t vpnkit . using the reported Windows 7 and Docker 1.11 environment. Inspect the opam repo add dev paths, the packages/local directory, and the reported topkg failure; the issue is done when the image builds without those errors.