As impersonated user, it is possible to delete impersonating user
Steps to reproduce:
1) Have 'admin' user and 'manager' user (with Manager role) both in the same taxonomies
2) log in as admin
3) impersonate manager
4) delete admin when impersonating manager
5) admin is deleted and user is now logged in as manager
It should not be allowed to delete impersonating user as impersonated user.