CORS issues behind nginx ingress after updating to JupyterHub 2.1.1

JupyterHub
7

I can confirm that the protocol header is lost on the way. I have changed jupyterhub/utils.py

def get_browser_protocol(request):
  ...
  # second choice: X-Scheme or X-Forwarded-Proto
 proto_header = 'https'

and the admin interface works as expected.