tests: fix user/user groups schema tests

rhodecode/tests/models/schemas/test_user_usergroup_types.py

@@ -22,6 +22,7 b' import colander'
 import pytest
 
 from rhodecode.model import validation_schema
+from rhodecode.model.db import Session
 from rhodecode.model.user import UserModel
 from rhodecode.model.user_group import UserGroupModel
 from rhodecode.model.validation_schema.types import (
@@ -72,8 +73,9 b' class TestUserAndUserGroupSchemaType(obj'
             err = exc_info.value.asdict()
             assert 'is both a user and usergroup' in err['user_or_usergroup']
         finally:
+            UserGroupModel().delete(usergroup)
+            Session().commit()
             UserModel().delete(user)
-            UserGroupModel().delete(usergroup)
 
 
 class TestUserType(object):