When <sub>.example.com domain is added to app on example.com cluster, ssl configuration is missing

Configuration
- Workflow 2.10
- `router.deis.io/nginx.platformDomain: example.com`

When I add FQDN (`sub1.example.com`) domain which includes my platform domain (`example.com`) and it isn't application name, then SSL configuration isn't created on deis-router(s). nginx.conf is missing whole SSL section for this domain. If I add just `sub1`, everything works fine. I'm not sure if it's a feature or a bug, I didn't found any mentions about this in documentation and it took my a while to figure out what is going on.