Did you click on the confirm email link twice? The first time you click it, the email is confirmed. The next time, we should show a message saying your email is already confirmed. But, we have a bug that doesn't show the message and redirects you to the register page.
We will recreate this issue and get it fixed ASAP. Do let us know if you are unable to login.
We will recreate this issue and get it fixed ASAP. Do let us know if you are unable to login.