CI Windows Shell Runner Hangs At End Of Stage

I'm trying to run the .gitlab-ci.yml file below, but the runner hangs at the end of the first stage without completing. It seems to complete if the python process is killed.

I'm using gitlab-ci-multi-runner 1.5.0 in Gitlab community edition 8.11

#.gitlab-ci.yml
stages:
    - setup
    - test

start:
  stage: setup
  script: 
    - "start python -m http.server"
    - "dir"

test:
  stage: test
  script:
    - "dir"