Unable to login to Bitbucket using Google login

Prerequisite: Two accounts signed in Google. One is paired with Bitbucket, second is not (no corresponding account in Bitbucket).

Steps to reproduce:

1. Go to login page and click Log in with Google button
2. Choose the account not paired with Bitbucket
3. You end up on register page asking for username
4. Click Log in
5. Click Log in with Google button
6. Select the proper account paired with Bitbucket
7. You end up on register page again