Unsupported reflection of expression-based index

I am getting the following warnings when running the ```loadanalytics``` command to retrieve GA statistics (https://github.com/ckan/ckanext-googleanalytics#setting-up-statistics-retrieval-from-google-analytics) with ckan 2.6.1 (not tested with previous versions)
```
/usr/lib/ckan/dcat/local/lib/python2.7/site-packages/sqlalchemy/engine/reflection.py:53: SAWarning: Skipped unsupported reflection of expression-based index idx_pkg_lname
ret = fn(self, con, *args, **kw)
/usr/lib/ckan/dcat/local/lib/python2.7/site-packages/sqlalchemy/engine/reflection.py:53: SAWarning: Skipped unsupported reflection of expression-based index idx_pkg_slname
ret = fn(self, con, *args, **kw)
/usr/lib/ckan/dcat/local/lib/python2.7/site-packages/sqlalchemy/engine/reflection.py:53: SAWarning: Skipped unsupported reflection of expression-based index idx_pkg_suname
ret = fn(self, con, *args, **kw)
/usr/lib/ckan/dcat/local/lib/python2.7/site-packages/sqlalchemy/engine/reflection.py:53: SAWarning: Skipped unsupported reflection of expression-based index idx_pkg_uname
ret = fn(self, con, *args, **kw)
/usr/lib/ckan/dcat/local/lib/python2.7/site-packages/sqlalchemy/engine/reflection.py:53: SAWarning: Skipped unsupported reflection of expression-based index idx_user_name_index
ret = fn(self, con, *args, **kw)
```

Any ideas?