stack build: 'InvalidAbsDir "(unreachable)/"' using docker on OSX

### General summary/comments (optional)
`InvalidAbsDir "(unreachable)/"` while building with `fpco/stack-build` docker image

### Steps to reproduce

```bash
git clone -b stack-docker-bug https://github.com/runeksvendsen/ufw.git docker-bug
cd docker-bug/
docker pull fpco/stack-build
stack build
```

[`stack.yaml`](https://github.com/runeksvendsen/ufw/blob/stack-docker-bug/stack.yaml)

### Expected

Successful build

### Actual

Error (`InvalidAbsDir "(unreachable)/"`) during build.

Verbose build log: https://gist.github.com/runeksvendsen/d7f87ef79f49e450895ba004444f4c68

### Stack version

```
$ stack --version
Version 1.6.5, Git revision 24ab0d6ff07f28276e082c3ce74dfdeb1a2ca9e9 (5514 commits) x86_64 hpack-0.20.0
```

### Method of installation

* Official binary, downloaded from https://github.com/commercialhaskell/stack/releases

### Further information

Docker for Mac: version: `18.03.0-ce-mac59 (dd2831d4b7421cf559a0881cc7a5fdebeb8c2b98)`
macOS: `version 10.13.3 (build: 17D102)`