[tz] Wrong symlinks with BACKWARD=backward PACKRATDATA=backzone

[Benjamin Drung]

On Wed, 2024-03-06 at 23:46 -0800, Paul Eggert wrote:
> On 3/6/24 13:29, Benjamin Drung via tz wrote:
> > the Debian/Ubuntu package uses BACKWARD=backward PACKRATDATA=backzone.
> 
> Why is that? In other words, what bug report prompted the use of 
> PACKRATDATA? That may help figure out a reasonable fix, if any is needed.
> 

This is the bug report:
https://bugs.launchpad.net/ubuntu/+source/tzdata/+bug/2003797

We have lots of users and some of them care about pre-1970 timestamps.
We want to satisfy them as well.

> > The resulting tzdata.zi has the timezone Africa/Asmara, but
> > Africa/Asmera points to Africa/Nairobi instead of the existing
> > Africa/Asmara
> 
> 'backzone' contains out-of-scope and often-wrong data dating back to an 
> older way of doing things. The 'backzone' data entries are not 
> maintained and are not necessarily compatible with the in-scope data in 
> 'africa', 'asia', etc.
> 
> There is tension between being bug-for-bug compatible with the older 
> tzdata, and being compatible with in-scope data and/or with other 
> platforms. The 'backzone' file is designed for the former case; this 
> minimizes maintenance effort, since it's relatively easy to just keep 
> the 'backzone' data the way it was. I wouldn't want to take on the 
> maintenance burden for the latter case, as that'd be quite a mess.

The goal is to get the pre-1970 data back, but keep it unchanged for
post 1970.

-- 
Benjamin Drung
Debian & Ubuntu Developer