avoid py3 NameError: global name 'e' is not defined
avoid py3 NameError: global name 'e' is not defined

https://travis-ci.org/alex/django-filter/jobs/79552463
https://travis-ci.org/alex/django-filter/jobs/79552465
https://travis-ci.org/alex/django-filter/jobs/79552468
alex/django-filter,newfylox/django-filter,newfylox/django-filter,alex/django-filter