This is a follow-up of report 8918 (work by Julian Maurice). That report introduces the new routine but only uses it in ILS-DI. This report is meant to extend its use in the Reserves module.
CalculatePriority is now mentioned outside of ILSDI too, so it has "spreaded" into the codebase. This bug has not enough information as is to see if we did all that was intended. Marking FIXED, please reopen if you disagree.