Bug in Set-QlikLicense when site has existing license

[aburnsy]

There is a line in Set-QlikLicense, where we check if we are updating a site's license and if the old license had a key. If both conditions are met, its assumed this is a downgrade of the signed license and we can't continue

if ($CurrentQlikLicense.key -ne "" -and $PSCmdlet.ParameterSetName -eq "Serial"

However, $CurrentQlikLicense.key is null, not an empty string, so that first statement is always true.