(We were hoping MDL-48187 would resolve this but it hasn't)

• back up a v 2.6.8 course that has Weighted mean of grades as the course aggregation method and contains sub-categories
• restore to v 2.8.3
• change the course aggregation method from Weighted mean to Natural: causes all subcategories and single grade items below get flagged as extra credit
• change the subcategory aggregation method from Weighted mean to Natural: causes grade items within the category to get flagged as extra credit.