This quickstart illustrates a bug where the InterceptData is never cleared.
This link goes to Secure Page, which requires login. You should see the login page, followed by Secure Page upon successful login. This is accomplished with RestartResponseAtInterceptPageException, which places InterceptData in the Session. The Login page then calls continueToOriginalDestination().
Click:
Secure Page via Login
This link goes directly to the login page. Since no RestartResponseAtInterceptPageException is used, and since the previous InterceptData should have been cleared by now, the continueToOriginalDestination() on the Login page will return false. This branch of the code should send you to the Success page.
However due to a bug, the InterceptData is apparently never cleared. Therefore the Success page is never reached. Instead, you will be sent to Secure Page because the InterceptData from step 1 is still in the Session.
Click:
Success page via Login