When all questions in a quiz are 'Not answered', regrading changes sumgrades from 0.00 -> NULL

1. As teacher, create a quiz. 2. As student, start an attempt, click 'Finish attempt...', and then 'Submit all and finish' without entering anything. 3. As teacher, go to Quiz > Reports > Grades, and verify that the mark for each question is shown as '-', and the attempt total is shown as '0.00' (number of decimal places depends on quiz settings. 4. Click the regrade all button. 5. Verify that the attempt total stays as 0.00, and does not change to 'Not yet graded' There is an alternative to step 4: 4'. Go to the Edit quiz page, change the Grade for a question, and click save changes. A. Also, create a quiz with some Essay questions. B. As a student make several attempts, leaving some (or all) questions blank, and other attempts were you answer some or all questions. C. As teacher, manually grade some of the questions. D. Then do the same thing as in 4. or 4'. E. Make sure that the total grade for the quiz attempt is only computed if all the questions in the quiz attempt are graded or gave up. Otherwise the quiz total should be 'Not yet graded'.