Question versioning: regrading does not work for all question types (including multiple choice)

Setup: Create a quiz. Add the following questions *: Multichoice Select missing words Drag-drop words-to-sentence Matching Multi-answer (see https://docs.moodle.org/400/en/Embedded_Answers_(Cloze)_question_type ). Short-answer. A second multiple-choice question. Attempt the quiz as a student. Note the score you got for each question. Log back in as teacher, and edit each question to change some of the wording of each question, but without making a structural change (e.g. don't add or remove a new multiple-choice option, just change its text. Except, in the second multiple choice question, add or remove a choice. Go to Quiz -> Results. Click the 'Regrade all' button. Verify that the regrade completes, but with a notice to tell you that Q7 could not be regraded. Review the quiz attempt. Verify that all the questions in the attempt look OK, and none of the scores have changed.   NOTE FOR THE TESTER : In order to save some time, you can also backup and restore in your local site the Demo Quiz with all standard Quiz Questions quiz from the Activity examples in the QA site and then add the missing questions.