My database server rebooted unexpectedly and I started getting this error each time I’d try to backup the database or do some other operations like dismount, etc. Cannot insert duplicate key row in object 'sys.syscommittab' with unique index '<Index Name>'. Failed to flush the commit table to disk...

I could not find a good description of how SQL Server Change Tracking determines if a column changed so I decided to give it a try in 2008 R2 using the script below.  Basically in the last update statement I update a column to the same value which already exists in the column.  SQL appears...