PageKite: need port in "frontend" setting

Created by: peacekeeper

If I enter markus.freedombox.me as "Server", then in /etc/pagekite.d/20_frontends.rc, Plinth writes the following:

frontend=markus.freedombox.me

But it should actually write:

frontend=markus.freedombox.me:80

If the port is missing, PageKite doesn't work at all. Of course I can put the full server AND port into the Plinth "Server" field. But this is not obvious, so I think Plinth should add the port :80 if it's missing.