405 error when logging in from non /login page

[tmthyjames]

No description provided.

[sparklespdx]

#30 is one way to fix this up. Our issue is that the 401 error handler is rendering the login page template for endpoints that aren't equipped to handle the LoginForm post. I'm handling this by actually redirecting to the login page instead, with the referring URL passed through the login page with the ?next URL parameter, and validating that parameter to make sure we only redirect to ourselves and not anywhere bad.

The end result is that you end up at whatever page you started out on before the redirect chain.

Patterned after this implemetation from Flask-Login: https://flask-login.readthedocs.io/en/latest/#login-example