At some point a regression was introduced in the login path. The app used to redirect the user to the URL they initial specified before they were redirected to the login screen. The user seems to always be redirected to the default page now.
Version: wmf-deployment
Severity: normal
Change 102969 had a related patch set uploaded by BryanDavis:
Store full URL in session when redirecting to login form
This was broken by a change made during the security review to validate the URL stored in the users' pre-authentication session. The redirect code now expects to find a full qualified URL rather than just the local route path.
Change 102969 merged by jenkins-bot:
Store full URL in session when redirecting to login form