Proposed change

If I understand correctly it is currently not possible to create named servers with systemdspawner.

If you set

c.JupyterHub.allow_named_servers = True

Creating a new named server will kill the original server. I think this is because the `unit_name_template does not expand the name:

c.SystemdSpawner.unit_name_template = f'jupyter-{USERNAME}-singleuser'

thus the "named server" has the same name as the default server and this the default server is killed...

Alternative options

• Not using named servers.
• Issue a warning when c.JupyterHub.allow_named_servers = True

(Optional): Suggest a solution

make c.SystemdSpawner.unit_name_template expand the (optional) name of the server