[tz] OpenJDK/CLDR/ICU/Joda issues with Ireland change

[Paul Eggert]

On 01/25/2018 03:25 AM, Stephen Colebourne wrote:
> Therefore, there are 8 possible combinations to consider:
>
> - new code, new TZDB, new CLDR - works fine
> - new code, new TZDB, old CLDR - wrong names
> - new code, old TZDB, new CLDR - wrong names
> - new code, old TZDB, old CLDR - works fine
>
> - old code, new TZDB, new CLDR - code may fail
> - old code, new TZDB, old CLDR - code may fail & wrong names
> - old code, old TZDB, new CLDR - wrong names
> - old code, old TZDB, old CLDR - works fine

This list of combinations is assuming a particular transition method. lf 
we use a different method we can avoid the failures that it mentions. 
One approach is to have an intermediate CLDR that is compatible with 
both the old and the new TZDB. I just now suggested something along 
those lines here:

https://mm.icann.org/pipermail/tz/2018-January/026002.html

Perhaps that idea wouldn't work as-is, but I'm sure that something along 
those lines would work.