anchor.diff:        // TODO: trigger consistency mitigation if more than one email exists
         if (usersWithEmail.length == 1 &&
             usersWithEmail.single.oauthUserId == null) {
  +        // Handle legacy logins that don't have 'openid' scope, and thus, no
  +        // user_id (oauthUserId), these can't be upgraded yet.
  +        if (auth.oauthUserId == null) {
  +          return usersWithEmail.single;
  +        }
  +
           // We've found a single pre-migrated User with empty oauthUserId: need
           // to create OAuthUserID for it.
           final updatedUser = await _db.withTransaction((tx) async {
  
positive.code:         return updatedUser;
        }
  
        final newUser = User()
          ..parentKey = _db.emptyKey
          ..id = _uuid.v4().toString()
  
negative.code:           info.userId.isEmpty ||
            info.expiresIn == null ||
            info.expiresIn <= 0 ||
            // TODO: Enable when pub client is requesting the correct scopes.
            // info.userId == null ||
            // info.userId.isEmpty ||
            info.verifiedEmail != true ||
            info.email == null ||
            info.email.isEmpty) {
  