Changing the top level realm's data store to use the mail attribute as the user search attribute prevents amadmin logins. The UI will display an empty page, and the following can be seen on the dev console:
- Install AM 7.1.0
- Go to embedded data store's settings and update LDAP Users Search Attribute to mail
- Attempt to log in as amadmin on a different browser
amadmin can still access the UI
admin console access is broken
amadmin has an empty string mail attribute value, which will translate to mail:  on the /json/users call, which will pass the if (!user.id) check in UserModel.js.