/admin view seems to require a login for the universal admin account

[Pomax]

Based on admin_protection.py only the universal admin account can log into /admin, raising questions on how others can log in without that... marking as bug because we have no idea what's going on.

This is pretty weird, and requires some django digging to figure out /cc @gideonthomas @hannahkane @simonwex

[cadecairos]

I'm pretty sure that there's only one possible admin account, and it's configured via environment variables.