SSRS 2012 Cannot Create Managed Account

Synopsis: When preparing to perform an in-place upgrade of SSRS 2008 R2 SP1 (SharePoint Integrated Mode) to SSRS 2012, be sure that the current SSRS service account is *not* already a SharePoint managed account.   Details: One of my latest tasks has been to assist a customer with an upgrade of their SQL Server 2008…