Cannot add "email" provider to an existing user

Case with no problems 1. User signs up with email provider. 2. A record is inserted to the auth.users table and ["email"] is set in the app_metadata.providers. 3. A record is inserted to the auth.identities table. 4. User signs in with signInWithOAuth() using a Twitter account that has the same email as the one registered in step 1. 5 A record is inserted to the auth.identities table. 6. Since the emails match, the user is considered the same and the app_metadata.providers in auth.users is updated to ["email", "twitter"]. 7. From now on, the user can sign in with either email or twitter. Case with problems 1. User signs up with a twitter provider. 2. A record is inserted to the auth.users table and ["twitter"] is set in the app_metadata.providers. 3. A record is inserted to the auth.identities table. 4. User tries to signUp() with the same email as the Twitter account used in step 1. 5. "User already registered." err…