The SAML authentication object is initialized with a particular HTTP host, and will reject any requests that come in with other hostnames. We've run into a case with a user where they want to use a reverse proxy for some users that give them a different hostname for the Review Board server, and while their proxy can rewrite URLs in requests and content, it's failing to handle the auth because of this. This change adds a step to allow any hostname which is properly configured in the `ALLOWED_HOSTS` setting to be passed through to the SAML library. Testing Done: - Ran unit tests. - Affected user reports that this solves their issue.