Ensure that the Grade field data stays in clean_data.
This prevents a bug that happens when you pick an invalid entry in the choice a grade field. If this bug was triggered the value of the survey_record.grade was used. Now however a proper ValidationError is raised.
[nosetests]
exclude=pymox
with-coverage=1
cover-package=soc
cover-erase=1
cover-html=1
cover-html-dir=coverageResults
#debug=nose.plugins.cover