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

[Michael H Deckers]

    On 2021-09-28 16:00, Paul Eggert via tz wrote:

> Many Zones in tzdb are "zones with data merged prior to 1970". 
> 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. That's a completely different
     matter.

     Micheal Deckers.