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.
1dc8d7f9458e3edeb8493e98d83bb0d1f679ca18 v0-5-20090604
19e9fdde919eeb9db11c9dd7cd4b35d13c29cf88 v0-5-20090608
96ff51144dca94573a51a07221422e0079c8801e v0-5-20090621
0dee663d6582060a7e152ed19fb8634b945e1770 v0-5-20090629
8f3a8e066111ff4ea1ce0e21379d144a3b1717cf v0-5-20090705
c7726e3ab1736237df0818aa57e5825e161b29c5 v0-5-20090705p1