[tz] Issues with pre-1970 information in TZDB

[Stephen Colebourne]

On Thu, 23 Sept 2021 at 13:41, Scott Kilpatrick via tz <tz at iana.org> wrote:
> In another thread, Paul wrote:
>
> > Locations in countries like Norway and Sweden got special treatment by
> being Zones, whereas locations in countries like Angola and Ethiopia
> were only Links.
>
> To which Robert Elz asked, why not instead resolve that discrepancy by restoring full data definitions, in the `africa` file, for Africa/Luanda and Africa/Addis_Ababa? That seems like a better resolution. After all, those two IDs had distinct definitions in the past, and then Paul converted them to Links back in 2014 (see commits [1] and [2], respectively).
>
> But really my question is whether Stephen C. et al would accept such a change. If Europe/Stockholm *becoming a Link and losing pre-1970 history* is an unacceptable change to data stability, what about Africa/Luanda *ceasing to be a Link and gaining pre-1970 history*?

It is one of the possible solutions that is acceptable to me. The
question is really "what rule determines whether an ID in the main
data files does or does not contain pre-1970 data".

Stephen