Discourse doesn't redirect to return_sso_url after user logs in on private site

[vinothkannans (Vinoth Kannan)]

It’s fixed as per below commits. @tdfischer can you please check again.

https://github.com/discourse/discourse/commit/ca7424665118e527eddbcb3c8bb764dd942585d7

https://github.com/discourse/discourse/commit/be6404d6519d03cfb9194bc03e5c6b9593513c1d