Michael H Deckers wrote:

   F2018L01702 is just the diff for the revised    version of Norfolk Island Standard Time Ordinance 2015    at [https://www.legislation.gov.au/Details/F2019C00010/Download].

   They seem to invalidate the diff after it has been    applied by Legislation Act -- it is probably not idempotent.

Thanks for the clarification. I installed the attached patch to the development version on GitHub to implement the change to tzdb, and something like this should appear in the next release. This change assumes that the fall-back transition on 2020-04-05 will occur at 02:00 standard time (03:00 local time), not at 02:00 local time, as this is common practice in Australia.