Steps to reproduce

1. In the "Security app" create 2 new accounts with the same roles and permissions assigned (e.g. "testUser" and "testUser(test)") 
2. Login with both accounts and go to the "Edit user profile".
3. User name without brackets works as expected, but the user name containing brackets throws an error.

Expected results

People whose user names contain brackets should be also able to change their profile information.

Actual results

Throws error.

Workaround

Development notes

Additional details and debug screenshots are available on the https://jira.magnolia-cms.com/browse/HELPDESK-1188.