you can clone system.git repository from workbench with all branches. Then delete broken user branch and push these changes back to workbench. That should resolve the issue with UI. system.git stores some user preferences and might be the cause of the issue. I believe there is UI way of resetting perspective but need to look into it to be sure it was included in 6.2.0.Final.
Please drop jira if you manage to find a way to reproduce it
It worked. Please let us know if there is a way to fix the user from the workbench UI. If able to reproduce the problem we will raise a ticket.
Here are the git commands for convenience:
// clone system
git clone ssh://krisv@localhost:8001/system
// list branches and pick the one to delete
git branch -a
// delete branch for broken user
git branch -d broken-uf-user
// push back to workbench
git push origin :broken-uf-user