[tz] Merged 1970+ time zones should always return -1 pre-1970

[Paul Eggert]

On 9/28/21 11:59, Michael H Deckers wrote:
>> America/New_York, for example, merges many regions that did not 
>> observe the same time before 1970. 
> 
>      Yes, but it merged only zones that _never_ had an entry in tzdb.
>      What we are doing now is merging tome zones that have existed
>      separately for years within tzdb.


There are many examples of those merges too. For example, Europe/Zurich 
currently covers Liechtenstein even though before 2013 there was a 
separate Zone for Europe/Vaduz.

And anyway, saying "we've always done it that way" would not be an 
adequate response to valid fairness concerns.