[tz] Extra transition for Europe/London with 2023d

[Paul Eggert]

On 2024-01-13 08:58, Brooks Harris wrote:
> That's a question I have. As far as I can tell zic creates only one 
> transition per day. There are examples in the source files where the 
> STDOFF changes at YMD 00:00:00 and there is also a DST shift at YMD 
> 02:00:00. That's two transitions in that day. But zic outputs a single 
> transition at YMD 00:00:00. While the formats could presumably handle 
> two transitions per day it appears zic combines them.
> 
> What is the TzDb policy here? Paul?

zic coalesces two transitions into one if they occur at the same time. 
But it shouldn't coalesce a transition with another one that occurs two 
hours later. If it does that, it's a bug in zic (and probably also a bug 
in the data).