When docker-compose up with the config below, if the file mypass.txt is missing, docker-compose creates an empty directory mypass.txt. Is that expected behaviour?

version: '3.1'

services:
  app:
    image: alpine
    secrets:
      - mypass

secrets:
  mypass:
    file: ./mypass.txt

macOS 10.13.1
Docker version 17.11.0-ce-rc3, build 5b4af4f
docker-compose version 1.17.0, build ac53b73