The "One-Shot" was also supposed to target ONLY new users but I have to admit it may on very rare occasions also accidentally target people who keep a clean computer with cache / cookie clean ups etc. or multiple browsers in play.
Standard forum oopsies if you will

Those users should be in the smallest minority (myself included as a tester for Arduino).
Although I have not yet been affected by it with my regular account.
The "other" re-direct to the forum selection page is excluded from this, as that is a separate and very annoying issue that is ongoing and bears no linkage to the "One-Shot"