Non-anonymous feeback with multiple submissions -> submissions cannot be modified anymore

There is an issue with the feedback activity using the following settings:

• Record user names: User's name will be logged and shown answers
• Allow multiple submissions: yes

We use this scenario for students to book certain courses via multiple choice elements. Back in M2.8 users could submit their answers and reopen the activity to review their selection or make changes to the selection -> initial answers where shown to the users.

Now in M 3.1.1 when users submit a feedback and repopen the activity they do not see their initial selection and if they submit the form a second time a second response will be created.

To reproduce:
1. Create a course with a teacher and a demo student
2. Create a feedback activity using the follwing settings:

• Record user names: User's name will be logged and shown answers
• Allow multiple submissions: yes
  3. Save/Open the activity and add a multiple choice question (single answer) with options "A" and "B"
  4. Log in as student, open the feedback and answer the question by submitting the selection "A"
  5. Reopen the activity and answer the question again
  6. The option "Not selected" is selected -> expected behaviour would be that option "A" is selected as this was the initial selection