Text to go in the release notes:
Before 18.05, suspension expiry date calculation didn't take the calendar into account. This behaviour changed with bug 19204, and some libraries miss the old behaviour.
These patches decouple overdue days calculation configuration (`finesCalendar`) from how the expiry date is calculated for the suspension through a new system preference: `SuspensionsCalendar`, that has the exact same options but only applies to suspensions. On upgrade, the new preference is populated with the value from `finesCalendar`, thus respecting the current configuration.