Rancher-compose up hangs at "Starting"

Rancher Version: v0.51.0
Rancher Compose: v0.7.0
Docker Version: 1.10.3
OS: OS X 10.11.4 Beta

I want to create a Gitlab instance on a remote rancher instance (which contains one host with multiple working stacks already).

Steps to Reproduce:

1. create this docker-compose.yml:

    io.rancher.container.pull_image: always
  tty: true
  image: gitlab/gitlab-ce:latest
  - /opt/gitlab/config:/etc/gitlab
  - /opt/gitlab/logs:/var/log/gitlab
  - /opt/gitlab/data:/var/opt/gitlab
  stdin_open: true

2. execute rancher-compose up


INFO[0001] Creating stack gitlab
INFO[0002] Creating service GitLab
INFO[0005] Creating service GitLab-Runner
INFO[0006] Project [gitlab]: Starting project
INFO[0006] [0/2] [GitLab]: Starting

It hangs forever at the last line.

In the webapp it looks like this:
rancher 2016-03-18 00-37-02