Login says it failed, but it actually worked

[matteosecli]

Describe the bug
Logging in on renkulab.io lands you on an error page, but the login is actually successful.

To Reproduce

1. Login on renkulab.io with valid credentials
2. You land on an error page on gitlab.renku.io
3. If you go back to renkulab.io, you're actually logged in

Expected behavior
No error or redirect.

Screenshots and/or execution output

Additional context
I believe I might have tried Renku 1.0 back in the days