bind-create-src option for bind mounts is ignored

[neben]

Setting this option on a bind mount should auto-create the source directory on the host. However, it has no effect and the task can not be created:

invalid mount config for type \"bind\": bind source path does not exist:

Here's the compose snippet:

    volumes:
      - type: bind
        source: /dir/does/not/exist
        target: /mnt,bind-create-src