There is a system option called 'Automatically Close Tenants after the Tenancy Closed Date'. By default this option is turned on, which means that when the tenancy end date is reached, the tenant is automatically closed. Previously people could turn this option off, which means that the tenancy end date can come and go and the tenant still remains open.
As a result of one of the fixes in the last version 8 release, turning this option off no longer works. A complaint I have previously received from clients is that the correct rent amount for the last rent period around the tenancy end date was not being calculated correctly. The rent amount would always be the full amount for the rent period, not a smaller amount if the tenant moves out in the middle of the rent period. So now the rent accumulation stops on the actual end date as set on the tenant details screen.
At the time of creating the 'Automatically Close Tenants after the Tenancy Closed Date' option it was not possible to set the tenancy end date to 'None'. Now that the ability to set the end date to None exists, this is the method that should be used if you want the tenancy to continue past the date originally set as the end date. Either that or set the end date to the new expected end date. The 'Automatically Close Tenants after the Tenancy Closed Date' option will probably be removed from the next release.
For those that want to keep a record of the original end date I suggest you either create a note or a custom field on the tenanst details screen to hold that information.
If this new way of handling tenancy end dates is going to be a problem for you, then I suggest you stay on version 7.9 while you consider the alternatives.