Cannot update user profile with non-internal auth method such as LDAP

Prerequisites

1. Docker

Setup

1. Run the docker CAS container:

   docker run --rm --name cas -p 8080:8080 -p 8443:8443 -dt moodlehq/moodle-docker-cas:dev

2. Login as admin to your site
3. Open Site admin => Plugins => Authentication => Manage authentication
4. Edit the settings for CAS
5. Set the following:
   1. Hostname: localhost
   2. Port: 8443
   3. Base URI: cas/
   4. Multi Auth: Yes
6. Save changes
7. Enable CAS
8. If you have an existing user with username 's10' delete it
9. Create a new user with:
   1. Username: s10
   2. Authentication method {{CAS Server (SSO)}

Testing

1. Browse to "Site administration" > "Users" > "Accounts" > "Browse a list of users"
2. Find the user that you created (Filter using "Show more" > for "Authentication" select "LDAP server)
3. Edit the user
4. Set:
   1. "Choose an authentication method" to "Manual Accounts"
   2. "username" to "testusernamechange1"
5. Click "Update Profile"
6. Edit the user again
7. Set
   1. "Choose an authentication method" to "LDAP Server"
8. Click "Update Profile"
   1. Confirm that you were able to change the user