Bug: Update user personal details is not working if the same username is used | CROSS PROJECT ISSUE

**Describe the bug**
Edit the personal information of the logged in user is not working.

**To Reproduce**
Steps to reproduce the behavior:
1. Go to 'My Space -> Profile -> Personal Details"
2. Change any field.
3. Save the changes
4. See error
INFO:werkzeug:127.0.0.1 - - [18/Sep/2020 11:07:36] "OPTIONS /user/personal_details HTTP/1.1" 200 -
CRITICAL:root:{'message': 'A user with that username already exists.'}
127.0.0.1 - - [18/Sep/2020 11:07:36] "PUT /user/personal_details HTTP/1.1" 400 -
INFO:werkzeug:127.0.0.1 - - [18/Sep/2020 11:07:36] "PUT /user/personal_details HTTP/1.1" 400 -

**Expected behavior**
Personal detail update should be successful

**Screenshots**
If applicable, add screenshots to help explain your problem.

**Desktop (please complete the following information):**
- OS: Fedora linux
- Browser: Chrome