- Checking out items on 24 May. - Loan period is set to 14 days. - useDaysMode is set to "Calculate the due date using the calendar to push the due date to the next open day." - Holiday set for 30 May. - Items are checked out with date due 8 June: 15 days. When calculating the due date the loan period should be extended by one day *only* if the due date would otherwise fall on the holiday date. In this case the due date is getting pushed forward just because a holiday falls between now and the due date.
I found this bug after I opened Bug 8418 - Koha::Calendar is_holiday ignores all user data which is basically a duplicate of this one. Sorry about that :-)
*** This bug has been marked as a duplicate of bug 8418 ***