[tz] [DRAFT] EU-related changes likely – here’s a heads-up

[Paul Eggert]

Jon Skeet wrote:
> Have you considered adding this to GitHub, but in a separate branch?

I considered it, but in the past I've avoided publishing multiple branches due 
to the complexity and confusion that they inevitably entail. Although larger 
projects need multiple branches, tzdb is a small one, and I would rather not 
maintain separate branches for each alternative-universe prediction of what will 
happen in Europe next year. We can install something along the lines of the 
patch at an appropriate point assuming the proposal becomes official and after 
further info rolls in. As the patch should affect only future timestamps, it 
shouldn't break too many people's cell phones when it's installed, and there is 
an advantage to sticking to a single prediction even if the prediction is wrong 
on some details.

The main point of publishing the patch now was not to predict what Finland or 
the UK would do: it was to point out technical details that need to be ironed 
out no matter what they do. The main problem, as I see it, is time zone 
abbreviations; a secondary problem is whether summer 2019 will be considered 
daylight saving time or standard time in Europe.