New Chronology for International Fixed Calendar

Hello joda-time stakeholders

Managed to implement a 13 month x 28 days a month calendar from the previous century.
What is NOT working is the the tests with zones, see TestInternationalFixedChronology lines 99 - 103.

It means that InternationalFixedChronology#getInstance (DateTimeZone zone) is broken.
Any idea how to fix this ?