PowerShell: User Group Policy loopback processing mode (UserPolicyMode)
<#
0 - Normal Mode (no loopback)
1 - Merge Mode
2 - Replace Mode
A reboot is not required for the changes to apply.
#>
[int](Get-ItemProperty -Path "Registry::HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\System").UserPolicyMode