[tz] Extended winter time

[Paul Eggert]

On 3/13/23 08:39, Tim Parenti wrote:
> our predicted March transition dates for 2024
> and 2025 also fall within Ramadan.

Also the years 2035-2058, 2068-2087, etc., if I estimated correctly.

When Ramadan occurs during midsummer, will there be four clock changes 
in the year? That is: spring forward in March, fall back before Ramadan, 
spring forward after Ramadan, fall back in October?

The Palestinian government may want to ask the Moroccan government how 
Morocco estimates dates for Ramadan, as Morocco also moves the clocks 
back during Ramadan. Although we cannot predict Ramadan exactly, we can 
use a conservative algorithm to choose a Saturday known to occur before 
Ramadan, and a Saturday known to occur after, and use those dates for 
the clock changes.

This is what we do for Morocco, as can be seen here:

https://github.com/eggert/tz/blob/1dd5133c04707a454e275032f6264b03f267638b/africa#L850